Basic test for instrumentation loading

Inspired by how we swallow failures during dependency detection to keep from
crashing, this basic test checks for errors when running detection with nothing
but the agent present.

This certainly won't catch every dependency detection failure, but it covers
the top-most level of each defer working when the dependencies in question
*aren't* available.
CHANGELOG update for 3.7.8.182
Merge remote-tracking branch 'origin/release' into dev
RUBY-1249 Don't break ability to pass a URI to Typhoeus (in versions 0.6.4+)
Now that we've dropped support for Ruby 1.8.6, update to mocha 0.14.0
We don't need to call before_setup/after_setup explicitly anymore - MiniTest will do so for us
Clean up ar_method_aliasing multiverse tests
Merge pull request #336 from newrelic/update-mocha

Update mocha to 0.14.0, paving the way for MiniTest 5 (and ultimately Rails 4.1 testing)
RUBY-1249 Fix version comparison in Typhoeus test
RUBY-1249 Don't needlessly ping-pong between URI and String for Typhoeus
Merge pull request #335 from newrelic/RUBY-1249

RUBY-1249 Don't break ability to pass a URI to Typhoeus (in versions 0.6.4+)
RUBY-1128 Convert Rails view instrumentation tests to a more standard form
RUBY-1128 Add a failing test case to demonstrate bad exclusive time in Rails 4 template rendering
RUBY-1128 Record exclusive time correctly for template rendering on Rails 4
RUBY-1128 Remove left-over pry reference in multiverse default Gemfile
RUBY-1116 Fix add_method_tracer usage when init_plugin has not been called
Merge pull request #337 from newrelic/RUBY-1128

RUBY-1128 Record exclusive time for template rendering correctly on Rails 4
Fixed typo
Use json instead of rubysl-json (which has been yanked)

Per brixen's comment here:
https://github.com/bundler/bundler/issues/2774#issuecomment-31967820
Don't try to run unit tests in an environment if bundling there fails