Disable two pylint warnings, W1201 and W1401, in .pylintrc.

These warnings are for:

:logging-not-lazy (W1201):
  *Specify string format arguments as logging function parameters*
  Used when a logging statement has a call form of "logging.<logging
  method>(format_string % (format_args...))". Such calls should leave
  string interpolation to the logging method itself and be written
  "logging.<logging method>(format_string, format_args...)" so that the
  program may avoid incurring the cost of the interpolation in those
  cases in which no message will be logged. For more, see
  http://www.python.org/dev/peps/pep-0282/. This message belongs to the
  logging checker.

:anomalous-backslash-in-string (W1401):
  *Anomalous backslash in string: '%s'. String constant might be
   missing an r prefix.*
  Used when a backslash is in a literal string but not as an
  escape. This message belongs to the string_constant checker.
Change coverage Makefile directive; use rcfile and TRIAL variable.
Add deprecation note in docstring of Bridges.is_valid_ip().
Fix old-style class bridgedb.Bridges.Bridge.
Fix old-style class bridgedb.Bridges.PluggableTransport.
Document `key` parameter for bridgedb.Bridges.BridgeRing.__init__().
Add CHANGELOG entry for BridgeDB-0.1.5.