Adds VisualAck to install list.
Tells ack to follow symlinks.
Adds an alias for amending git commits.
Updates PATH variable. Adds npm userconfig file.

Removes npm-installed binaries from PATH as they should now be symlinked
into the /usr/local/bin directory.
Quote path to load RVM into the shell session.
Replaces git aliases and refactors configuration.

Adds section for branch configration options.
Adds additional diff tools and sets default diff tool to SublimeMerge.
Adds additional merge tools.
Adds rerere sections. Enables rerere to record how to resolve conflicts
during a "test" merge and reuse the same approach when resolving the
same conflict during a "real" merge.
Adds configurations for RubyGems and RVM.