Drop the use of nohup on OSX for tmux compatibility

Apparently `nohup` is not needed in OSX, and using it has the side
that it may break under tmux with the error

  nohup: can't detach from console: No such file or directory

For now, this commit only drops the use of `nohup` in OSX. But it
*may* not be necessary under other similar platforms.

gradle plugin: also list tasks in subprojects
Cleanup gradle plugin file

- Delete useless #!zsh
- Simplify gradle build file check
- Format comments and delete TODO stuff (already dealt with)
- Use `$()` syntax for cat commands

dircycle: remove redundant key bindings

Removed Similar Aliases

bundle outdated alias

Fixing strange git unstaged prompt behavior

Mercurial plugin: revise README

In bindkey strings, "^[" and "\e" mean the same thing. They're both notations for Escape.

Closes #4616
Changes the `plugins=(... mercurial ...)` to be closer to correct zsh syntax, removing commas and extra spaces.
Revises discussion on configuring themes to avoid sounding like users should modify the theme definition file in the main OMZ folder. Prioritizes the suggestion of using a theme which already supports hg_prompt_info.

Two similar aliases which were causing issues.

use capit instead of shipit as shipit conflicts with npm package shipit

typo: able take -> able to take

I noticed that for certain projects with unstaged changed I would get a 'U' character instead of the '●' character. This should fix that.

[README] Update custom directory command and fix code blocks

Fix typo.

Close #4016

* `cfp` alias was referencing an old version of the `cf` command which
no longer exists. This has been updated to reference a valid command.

[FIX ERROR] Refactor for function in plugins/rake-fast/rake-fast.plugin.zsh

Really this time :P

Fixes #4533

We need to use POSIX syntax. This file is no longer executed with zsh.

Fixes #4483.

Drops the `function` keyword and uses only `func(){}` syntax as per the
POSIX specification:

http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_09_05

Related: #4531

This reverts commit c9d93757, which
makes it fail with a syntax error:

  sh: 1: Syntax error: "(" unexpected

Fix "be" -> "b" typo in coffee plugin README.md.

Fix install.sh/upgrade.sh for tput-less systems

Check for git before trying to upgrade OMZ

chucknorris: add missing line/quote delimiters

Make install script safer

This changeset wraps all of the commands in tools/install.sh in a
function and then calls that function as the last line of the
script.

The current install instructions ask the user to download the install
script using `curl` and pass the result to `sh`. This is totally
fine (as long as both the instructions and the script itself are served
using HTTPS), but the script should be written in a way such that it
doesn't start trying to actually *do* anything until the very last line.

The reason is due to the way `curl` work: if the socket drops before the
request is complete (server abruptly hangs up, client's internet flakes
out, etc.), `curl` will return the partial data that it received. Here
is an example of that:

![partial file execution](https://cldup.com/qU_Mnh2GmT.png)

A way this might cause issues for tools/install.sh is if the connection drops
after cloning but before the repository (L53-56). The .zshrc
configuration will not be copied and the shell will not be changed, but
if the user tries to run the install script again it will claim
oh-my-zsh is already installed (L31-39).

While this is not a particularly dangerous error condition (the user can
just delete .oh-my-zsh and re-run), it can certainly be confusing for
new users. This also helps future-proof the script for a time when it
might need to use a "dangerous" command, e.g. `rm`, and we want to make
sure it happens in the most transactional way possible.

[FIX #4525]: Fix typo