dxpy: Import requests via an absolute path
Merge remote-tracking branch 'origin/import-requests-absolutely' into PTFM-13951-retry-connection-errors

Conflicts:
	src/python/dxpy/__init__.py
dxpy: Import requests via an absolute path

This eliminates the use of an import name substitution shim (in the
placeholder dxpy.packages.requests module) that has proven to be
problematic.
Retry socket.error with certain error codes.

Add some quasi-tests that indicate the desired behavior.
Merge remote-tracking branch 'origin/master' into PTFM-13951-retry-connection-errors

Conflicts:
	src/python/dxpy/__init__.py