Add module to support HTTPS requests.

Add module to support HTTPS requests.

-New program arguments to configure http requests:
+http.user-agent
+http.connect-timeout
+http.transfer-timeout
+http.ca-path
-Relocate functions that create a local directory structure from a local URI, so that can be utilized by rsync.c and http.c.
-Expose a function to download a file from an HTTPS URL, the function is expected to write the bytes from the response into a file using a callback (defined by the caller).
-Add libcurl dependency at makefile and docs (still needs an update for the distinct OSs installation).
-Add unit test for the http module.
-Update man and docs with new configuration properties.
-Update configuration example with new configuration properties.