CIB: Fix for OSDL #1385 - Corrupted config file prevents heartbeat restart
We now differentiate between "couldn't parse the XML" and "digest checks failed".
When a file exists but does not contain valid XML, then we disable disk writes

(so no information is lost) and continue with an empty configuration in the
hope that another node can supply the correct one to us.

Patch contains additional improvements to the CIB startup code.

• more appropriate error codes
• better error messages
• makes the configuration queryable in more error cases
• removed redundant code

Mercurial revision: b0133fd0b88b4d0a5faa90bd8642c359ab10643a