update.py fails silently if module is not found

update.py can be used to copy individual modules into OpenStack components by
using the --modules switch and providing a module name. However, if this module
is not found is oslo, the user is not informed that the copy failed. Print a
message in this case, and provide the path to the file that the script tried
to copy.

Change-Id: I6f811cd9a412d83a4d83f29c8f8398ca0503f7f4
Closes-Bug: #1274647
Skip __pycache__ in maintainers check

When tox runs, tools/check_maintainers.py fails with an error
``Directory __pycache__ not found in MAINTAINERS``

This happens, because unittest on py33 was merged to master, and
python 3 stores bytecode in the __pycache__ folder. So we should
not check an entry for this folder in MAINTAINERS file.

Change-Id: I3f311f37262739e50a59164e204d8ff806f5f408
Merge "update.py fails silently if module is not found"
Merge "Skip __pycache__ in maintainers check"