check if the rack_env is set
RUBY-1400 Don't use hw.activecpu to determine logical processor count

This is a Darwin-specific sysctl, and isn't really even useful there - sysctl.h
explains it as:

The number of processors currently available for executing threads. Use this
number to determine the number threads to create in SMP aware applications. This
number can change when power management modes are changed.
RUBY-1400 Don't use hw.availcpu to determine logical processor count

This appears to be Darwin-specific, and sounds like it might behave in a similar
way to hw.activecpu in that it can change depending on power management
settings. In any case, I think hw.ncpu is more widely available, so there's no
reason to have a fallback to it.
RUBY-1400 Separate out freebsd and darwin CPU info gathering code paths
Include ActiveRecord tests on 2.1 and 2.2

Prep for covering everything we do in unit tests via multiverse instead
Wire up tests to mysql instead of SQLite

Takes a bit of doing to accomplish this (mostly) withou Rails, but gets
us to where we could move over the unit tests pretty cleanly on all
tehse versions
Move unit test reliance on databases to multiverse
Don't need sqlite3 anymore in these tests
Bad idea putting models in place that Rake migrations load
JRuby + ActiveRecord 2.2 fussing
RUBY-1400 Redirect stderr on sysctl calls from SystemInfo
RUBY-1406 cache SSL cert store

Instead of re-parsing all 47 certs in our cacert.pem file every time we need to
establish a new connection to the collector, this change makes it so that we
cache the parsed CA bundle in an OpenSSL::SSL::Store object hanging off of the
NewRelicService object.

The store will be lazily created, and only re-generated if the requested cert
file path changes (e.g. because of a config change).
RUBY-1404: Add Grape instrumentation, start testing.
RUBY-1404: Added error handling and non-Grape endpoint pass-through.
RUBY-1404: Pull string literals out into separate module.
RUBY-1404: Test setting Grape transaction names.
RUBY-1404: Use ensure block to name transactions.
RUBY-1404: Add Rack::Builder to app so we record metrics.
RUBY-1404: Add disable_grape config.
RUBY-1404: Move Grape constants to module.