(maint) Add string utility function for display CPU speeds.

Adding a "frequency" string utility that creates a display string for
CPU speeds from a integral frequency.
(CFACT-124) Refactor the processor resolver.

Refactoring the processor resolver so that a base type is responsible
for defining the fact and the child types are responsible only for
collecting data.

This commit also makes the processors structured fact consistent between
all platforms.
(CFACT-124) Add unit tests for base resolvers.

Adding unit tests for base resolvers that test the fact definitions.
Merge pull request #156 from peterhuene/refactoring

    * peterhuene-refactoring:
      (CFACT-124) Add unit tests for base resolvers.
      (CFACT-124) Refactor the processor resolver.
      (maint) Add string utility function for display CPU speeds.