Fixed filtered scope host not used in request headers

Conflicts:
	lib/intercept.js
Fixed issues with mismatching case header names
Fixed an issue with request header not set to filtered scoped host
Fixed request header matching for special case of host
Added suppress_reqheaders_recording recording option
Renamed headerKeysToLowerCase to headersFieldNamesToLowerCase for clarity
Set the storage of headers field names to lower-case throught Nock
Changed semantics of recording options with enable_reqheaders_recording
Header field user-agent is now deleted case-insensitively
Merge branch 'fix-request-header-matching'