Changed shell to bash

The script depends on specific bashisms (see issue #1).

Changed the interpreter call to reflect this.
Improvements: case-insensitivity, whitespace

Added two minor improvements to the script.

1. BUGZID string is now case insensitive.
2. Whitespace around the bug number does not lead to errors.

This means that instead of

	BUGIZD:123:Text...

the following case identifier is now also accepted:

	bugzid: 123 : Text...
Merge pull request #2 from l3m/improvements-only

Improvements only