Replace line-continued strings by multi-line resp. parenthesised strings.

These are easier to read and maintain.
Fix: MANIFEST.in does not properly exclude .pyc and .pyo files.

Need to use "global-exclude" instead of just "exclude" and need to
exclude *after* including all PyInstaller files.
Enh: put hard-coded git-revision into dist-packages created with setup.py.

This replaces PyInstaller/utils/git.py within the dist/build by a
fake-module which always returns the current git-revision. The original
source-file is unchanged.

Fixes issue #753.
Keep file-mode of PyInstaller/utils/git.py when writing fake-file.