minor refactoring in RequestParser: rename it into ParsedHttpRequest;
reformat the code, add finals and do minor optimizations
added one unit test for TestParsedHttpRequest
TestParsedHttpRequest unit test passes
add testHeaders() unit test; created setUp() section
added two more tests to TestParsedHttpRequest
Merge pull request #816 from Microsoft-CISL/sergiym_http_server_tests

Add some unit tests for the ParsedHttpRequest class; refartoring