Making some useful changes to vimrc.

* Highlight current line.
* Remap the leader key to ','.
* Remap ESC to 'jj'.
* Add more files to ignore.
* Turn on smart case-sensitive searching.
* Stop the help from coming up when you accidently hit F1.
* Add a '<leader>W' as a macro to trim all trailing whitespace.
* Add a '<leader>a' as a macro for Ack.
* Add two macros to edit or reload the vimrc.