Move wrapped C library to subpackage

Move wrapped C library to subpackage

Create new subpackage rmr/rmrclib with the C library loaded via ctypes.
Add method to get constants from RMR library that recognizes mocks.
Split test files into test_rmr and test_rmrclib.
Extend sphinx configuration to mock the rmrclib subpackage.
This change allows generation of API documentation by Sphinx
when the .so file is not available and the import would fail,
for example at ReadTheDocs.

Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>
Change-Id: Idb9bb1d7a534c4142ea0353b5a48d3132e55f6e6