append to files and more robust options

adds the ability to append an alias to bash_profile as well as append
the pgpass string to pgpass.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.md
	lib/db/heroku/command/db.rb
remove append_to_file method no longer used
Merge pull request #2 from leklund/master

Alias format, multiple format support, and better options handling.