Adds 'vlm' alias for editing last rails migration file

Nearly every time a Rails migration is generated, you wish to do some manual
changes to the migration file before running it.  The 'vlm' alias opens
the last migration file in the db/migrate file in vim.
Adds two more bhaskell git aliases

`g = git` cuts out two characters for every non-alias git command.

`gdc = git diff --cached` is a quick way to examine what's been staged.
Merge pull request #14 from rvandervort/master

Adds 'vlm' alias for editing last rails migration file

Nearly every time a Rails migration is generated, you wish to do some manual
changes to the migration file before running it.  The 'vlm' alias opens
the last migration file in the db/migrate file in vim.