Add a hook for the keyring module
Add comments to keyring hook
Add hook for keyring package.

Python keyring package:
https://pypi.python.org/pypi/keyring
Add test for keyring package.
Add license to hook file.
Add license to test, as well.
added excludes option
add test_exclude_module
update manuals with --excludes command documentation
Merge pull request #1100 from bjones1/develop

Fix: Support Linux installations without python-kde4 installed.
Add pointer to build instructions to bootloader-Readme.
Add debug output: Print name of script to be run.
modified command-line utilities '--excludes' into '--exclude'
and made it repeatable
Fix #900: Print message that Python 3 is not supported and fail.

I've put this into PyInstaller/__init__.py, so *none* of the Pyinstaller-
tools will work with Python 3, not even archive-viewer nor makespec. If
this is not desired, we can move it into PyInstaller/build.by
Fix #910: Remove -o option from manual.
Update usage-options in man-page for build, make_comserver, makespec.
Fix #1105: Cache corrupts exension modules with same basename.

Eg. both `_random.so` and `subpackage._random.so` have been stored as
`random.so` into the cache. Now take the `dist_nm` if available.
Put some comments into empty files do make them non-empty.
Add missing copyright header to some hook-files.
Issue #589: Add test-case to ensure empty hook-files are useless.