usql v0.6.0

Release v0.6.0 has some minor feature additions (syntax highlighting), and general code cleanup. A list of the major changes:

• Syntax highlighting
• Better compatibility with psql commands
• Homebrew support

To install on OSX via Homebrew:

# add tap
$ brew tap xo/xo

# install usql with "most" drivers
$ brew install usql

# install usql with oracle and odbc support
$ brew install --with-oracle --with-odbc usql