Low: parse: Stricter parsing of resource names

Require that resource names start with an alphabetic
character or _, # or $. Refuse empty resource-matching
patterns.
Low: xmlutil: Fix resource reference detection for rsc_location

Assumptions made about the structure of rsc_location may no longer
be accurate given the use of resource patterns or resource sets.
Low: cibconfig: Detect invalid regexes in rsc-pattern
Dev: unittests: Add failing rsc-pattern test