RUBY-1358 Add Rails 4.2.0.beta1 to rails multiverse suite
RUBY-1358 Adding rails42 environment with Rails 4.2.0.beta1
RUBY-1359 add HTTP status code to analytics events
RUBY-1359 Freeze string constants used as keys in RequestSampler
Add more logging around unexpected timings for metrics.
Fix invalid variable name

When an environment is not included in a config the following error is printed in newrelic log:

```
NameError: undefined local variable or method `path' for #<NewRelic::Agent::Configuration::YamlSource:74268300 {}>
```
Rename referringPayload to inboundPayload in CAT map tests
Make it easier to copy/paste from the output of the path_hash script
Add expected outbound CAT payloads to CAT map test cases
Verify outbound CAT headers in CAT map tests
Rename expectedAttributes, nonExpectedAttributese in CAT map tests
Update cross_agent_tests README with details about CAT map tests
Merge pull request #719 from ruby-agent/rails42beta

RUBY-1358 Run tests against Rails 4.2.0.beta1
Reduce allocations in RequestSampler by 1 per txn
Log more aggressively on odd metrics, and add a cap to how many keys
`log_once` hangs on to.
Merge pull request #731 from ruby-agent/request-sampler-allocations

Reduce allocations in RequestSampler by 1 per txn
RUBY-1363 Do not log a warning about the NEW_RELIC_ENV environment variable
Merge pull request #728 from ruby-agent/more_logs_for_odd_metric_times

Add more logging around unexpected timings for metrics.
Merge pull request #732 from ruby-agent/RUBY-1363-no-warn-on-new-relic-env

RUBY-1363 Do not log a warning about the NEW_RELIC_ENV environment variable
Added test/performance/script/log/ to .gitignore