storage-conf.xml reformatting

Our sample config (conf/storage-conf.xml) is the canonical source of configuration documentation. As such readability should be a priority, and it should serve as the best possible basis for customization.

I propose the following:

1. Wherever possible, lines should wrap at 75 chars. The file will be edited post-installation by operational personnel, who are often confined to standard 80 character terminals.

2. Indention of 2 spaces to make maximum use of horizontal real estate.

3. More distinctive multi-line comments.

4. Path locations that conform to the FHS.

Patch to follow...