Update install script

- Create error checking for repository downloading
- Create error checking for tarball extraction
- Update invalid option with `run_help` to show available options
- Create `check_xcode` method
- Update install script to utilize `check_xcode` function in order to use
  it recursively
- Update `type_exists` utils function with messaging to better control
  output messaging
- Change `brew linkapps` to use `--local` flag in order to install all
  applications under user directory
- Update all package installation success messages to point to
  installation directory
- Update order of package installation to be more consistent with
  lexicographical order already in place
- Remove git config check as it was checking for missing gitconfig;
  .gitconfig is created in a previous step from `mirrorfiles`
- Remove not operand on ViM check as it prevented the script from ever
  entering the bundle installation
- Remove `HOMEBREW_CASK_OPTS`; user installed applications should be
  installed to the user directory
- Update inputrc to use ViM bindings
- Update bash options to use variables in the prompt
- Remove bash completion script from bash_profile; update with Homebrew
  installed bash completion
- Update bash prompt with @necolas updated $TERM string check
- Create global git config
- Update vimrc with various tweaks found from @mathiasbynens
- Remove incorrect variable from vimrc as it wont work; update with
  correct path definition
- Update `run_brew` function with ctags library installation
- Remove php55 installation from `run_brew` function as it belongs in
  ./lib/php
- Create separate installation step for QuickLook plugins as it requires
  guaranteed creation of folder structure; remove from current
  ./lib/cask/default
- Update brew cask installation packages with correct names
- Update cli tools installation success message with correct file path
- Remove unneccesary line breaks from failed script messages
- Remove powerline installation from pip function as I'm moving to a
  different ViM plugin that doesn't require python (bling/vim-airline)
- Update error function in utils library to exit with status 1
- Update `install_xcode` function to check if you're using the correct
  version of OS X as it requires Mavericks for the updated `--flag` on
  `xcode-select`, add verbosity, as well as create checks for user input
  to ensure xCode is actually installed.
- Update `installcask` function to be verbose
- Create 'are_you_root` function to check if you have administrative
  privileges. May use later on

Issue: #9