Fixes file mode bits of compute/manager.py

Modified file permission from 755 to 644.
Removed a redundant blank line to avoid merged errors in gerrit
which happens if no content has changed.

Partially fixes bug #1224226

Change-Id: Ia300ac05fbeb251bb801cec44011df94ce8f16b0
Merge "Fixes file mode bits of compute/manager.py"