Take the nuclear option for a bare except

Destroy it with fire
Correct too terse variable name
Fix tests that were broken by broken by config loading changes

Changes I made to the way that additional config sections were loaded in
shavar.main() broke some tests.  Fix those.

This is most likely just an interim measure until I have fun with mozsvc.
Use enumerate() instead of line counting explicitly
Typo fix
Stop being stupid about calls to strip()
Rename all has_prefix to find_prefix
Only calculate the list 'o chunks at data load time

And make list_chunks() return value less confusing to the eye
Remove reference to as yet unimplmented class
Fix multiline string readability nit
Remove yet another reference to as yet unimplmented class
Whoops.  Missed two references to DirectorySource
Switch to using ValueError instead of ParserError

Also remove an unused data member from ChunkList
add_chunk was definitely confusing; rename to insert_chunk