RUBY-1152 Renamed ErrorCollector#harvest_errors to #harvest, in line with other harvest containers
RUBY-1152 Add an (as yet unused) harvest_and_send_from_container method

This new method will be the chokepoint through which all interaction with data
containers (TransactionSampler, ErrorCollector, StatsEngine, etc.) will flow.

It is not used yet, but is tested.
RUBY-1152 TransactionSample#prepare_to_send! now called from TransactionSampler
RUBY-1152 Switch metric data to harvest_and_send_from_container
RUBY-1152 Switch slow SQL to harvest_and_send_from_container
RUBY-1152 Switch errors to harvest_and_send_from_container
RUBY-1152 Switch analytics events to harvest_and_send_from_container
RUBY-1152 Multiverse test clean-up to deal with harvest changes
RUBY-1231 Move BrowserMonitoring to class JavascriptInstrumentor
RUBY-1152 Rename StatsEngine#reset_stats -> reset! in line with other data containers

Also, rename NewRelic::Agent::Agent#reset_stats to drop_buffered_data, since it
now resets much more than just stats (and honestly has for quite some time). And
do the same for NewRelic::Agent.reset_stats.

Aliases remain in place for the reset_stats calls on Agent, Agent::Agent, and
StatsEngine.
RUBY-1231 Stop depending on BeaconConfiguration
RUBY-1152 Review feedback: rename harvest -> harvest! to indicate mutation

For data containers (StatsEngine, TransactionSampler, SqlSampler, etc.) the
harvest! method should be implemented as a superset of reset! - that is, it
should drop and data buffered in the container and hand it back to the caller.
Because it mutates the state of the container, we're suffixing it with a '!'.
RUBY-1231 Move over to using JavascriptInstrumentor
RUBY-1231 Log JS agent settings after collector's called back
RUBY-1231 Test clean-up
RUBY-1231 Cleanup on JavascriptInstrumentor

Consistency in applying insert_js? check (formatting and logic)
More idomatic usage throughout
Removed unnecessary method abstractions (generate_footer_js)
CHANGELOG for 3.7.0
Merge pull request #283 from newrelic/changelog_370_beta

CHANGELOG for 3.7.0
RUBY-1231 Rename on js_data to data_for_js_agent
RUBY-1231 Rename on extra_data to be more expressive