Updating installer for better Windows compatibility.

On Cygwin hosts, use a hard link instead of a symbolic link for each file. This ends up using a Junction, meaning it's understood by Windows (and not a small file containing metadata).
Adding vim-like quit alias, updating HISTIGNORE.

Also setting wget user-agent to IE 10 on Windows 8.
Fix git commit shortcut
Add some settings to `vimrc`
Improved platform detection code.

* Platform-specific directories are now lowercase, and Cygwin doesn't need its own special rules repeated - "uname -o" is not available on OS X, and gives better output for Cygwin only.
* Change in ls behaviour is now determined by a check for what distribution of ls is in use. GNU and BSD ls are different in how they handle colours, and this is detected at the top of the script. The variable $COREUTILS will contain either "GNU" or "BSD" and can be used for additional scripting.
* `chmod +x bin/darwin/*`
Update readme