rum: circuit breaker for lack of js_agent_loader code
rum: disabling of rum during a ForceRestart exception

We trip a circuit breaker when 'browser_monitoring.loader' is changed by
the server. This value is sent every connection, and is updated to
reflect if rum is enabled or not.

from: @nrn only disable rum when load explicitly set to 'none'
test: DRY the rum test code
config: ignore status codes sent by server
api: custom parameter support
api: ignoring overrides custom parameter setting
docs: adding myself to the contributors list.
docs: add note about running services
src: bootstrapping and startup failurs distinguishable
instrumentation: split up MongoDB error messaging
docs: typo in socket.io ignoring rule
api: add custom parameters to error noticing
api: add high-security mode compliance
log: error message when high-security mode fails

If an agent tries to connect to a high-security
account without passing a comliance check,
the agent will be rejected immediately.

We want to let user know this as soon as possible.
collector: fix socket hangup error
docs: update release notes
1.5.0
test: update string to support new version of mongodb
config: add feature flagging
config: warn when unused flags in user config