fixed httpserver.r2py to work properly for Repy v2 and new unit test for it

[us341]

No description provided.

[choksi81]

• I ran the unit-test designed to test the updated httpserver.r2py and the test got pass. So no issues there.
• There is one thing I would like to mention though. There is a call to httpserver_sendfile_chunked in httpserver.r2py (https://github.com/SeattleTestbed/seattlelib_v2/pull/150/files#diff-d1237daea38f8ad8d8d5a35da2e295b2R895) which in turn calls filelikeobj.read(). This "read" call or the call to " httpserver_sendfile_chunked" hasn't been handled under try-catch block to catch the exceptions. I may be wrong, but this is one issue I though I would mention.
• Otherwise the PR is good to be merged.

[choksi81]

May be try-catch block is required here or in httpserver_sendfile_chunked to handle the "filelikeobj.read" exceptions?

[us341]

filelikeobj is object of _httpserver_StringIO class and read() is calling this class's read method. It is handling the ValueError if the class object is closed.