RUBY-1020 Don't create the AgentLogger over again

Our DJ instrumentation calls init_plugin multiple times, but this seems to foul up the PG
database connection, which gets closed before destroying the first completed job.
RUBY-1021 Apply error queue limit to Resque child errors

The pipe communication between the Resque workers and the parent was side-stepping the
limit we place on number of errors to return to the collector. Now we apply the same cap.
RUBY-1021 No Array#count in 1.8.6. Sigh.
RUBY-1017 Signing the gem
RUBY-1017 Only sign gem if we find the keys

This is necessary to support bundler pointing to a git repo.
RUBY-1017 Don't generate message on gemspec failure to sign.

Shows up during application startup on STDOUT, which is not a great idea.
Don't need to inflict that on everyone running with :git => ... in their bundle.
RUBY-1017 Regenerated cert before release
RUBY-1019 Use pattern matching for handling HTTP response logic

Refactor for better readability
RUBY-1019 Make NewRelicService responsible for http_connection and ssl cert

This was being handled by Control which led to a bunch of back and forth
references between these objects.  Move responsibility for managing
tcp/http connection to the service so it can manage keep alives, etc.
RUBY-1019 Implement http keep-alive

HTTP requests can be pooled under one tcp connection by calling them
from within block passed to NewRelicService#session
RUBY-1019 Add some unit test coverage for NewRelicService#session

Check that keep-alive implementation is behaving correctly
RUBY-1019 Add session interface to PipeService
RUBY-1019 Remove unnecessary code

Thanks Jason!
RUBY-1019 Old versions of mocha don't support #unstub

Extract these tests to another test class so they can have a different
setup.  Our rails 2.x tests fail because #unstub wasn't an option back
then.
RUBY-1019 Add some more debug logging around collector calls
RUBY-1019 Use keep-alive for harvest calls to collector
RUBY-1019 - Fix Webrick misconfiguration that messes up keep-alive

Webrick thought we wanted it to use nil as its access log.  It would
succeed on the first request, then experience an error writing the
access_log that looked like this:

ERROR NoMethodError: undefined method `+' for nil:NilClass
  webrick/httpserver.rb:213:in `block in access_log'
  webrick/httpserver.rb:212:in `each'
  webrick/httpserver.rb:212:in `access_log'
  webrick/httpserver.rb:111:in `run'
  webrick/server.rb:191:in `block in start_thread'

This error would screw up the TCP connection and subsequent requests on
that TCP connection would fail.  This was never a problem until we
implemented keep-alive.
RUBY-1019 Add log warnings when SSL is not configured

Conflicts:
	lib/new_relic/agent/new_relic_service.rb
RUBY-1019 SSL is now the default transport
RUBY-1019 Fix logic bug in log messages