Added 6 QLPlugins via Brew Cask

The QLPlugins are:
* qlcolorcode
* quicklook-json
* qlprettypatch
* quicklook-csv
* betterzipql
* webp-quicklook
* suspicious-package
SSH Keys added to the System ssh agent

By doing this it adds the generated RSA key to the authentication agent.
Added a section to install cmd tools

Gives the user an option to install command line tools only via OS X.
Remove dependency on needing Xcode installed if not desired.
Added a section that downloads Android SDKs
Fixed typo
Removed the wget for android and used Brew

why use wget when you can use homebrew? Can't use the platform tools
formual with the android-sdk pacakge as conflict. Use of sdk via command
line deals with installing it without needing to launch GUI.
Merge pull request #1 from lordqwerty/master

Minor changes to MainInstaller.sh