Pugnacious Pig

Features:

• Integration of new request library, allowing routing through target specified by proxy environment variable. New library turned off by default for now. To turn on, set use_requests_lib.

Bug fixes:

• Fix windows_system_metrics monitor to no longer report disk usage on empty drives
• Fix mysql_monitor to recreate connection to db on failures
• Fix metrics names rather than throw errors when invalid metrics names are emitted by modules such as graphite.