Changes to test support for remote database hosts and reverse proxies

* Added a testing suite for aws rds mysql database
* Updated the server test suite to verify FROG_URL, MEDIA_URL, and STATIC_URL properly
* Added libmysqlclient packages to supported platforms so MySQL-python builds properly
* Added a new library that provides generate_url() for normalized URL generation
* Added spec tests for new library function
* Added a new port parameter to node['frog']['settings'] to allow better control over
  the FROG_URL, MEDIA_URL, and STATIC_URL settings.
* The server.rb recipe now uses generate_url to pass into the settings.py template
Fixes for settings.py url, media_path, and static_path variable tests
Merge pull request #2 from nickryand/rds-proxy-fixes

Rds proxy fixes