Add standard compiler flags and options for AIX
Don't send ldd/otool output to the same file.

This will allow multiple omnibus project builds to run concurrently
(with separate cache dirs).

* GC concern in the original comment is addressed in mixlib-shellout 1.4
* it should be fine holding entire shell output in memory as it's doing it already.
  currently, it redirect all output to disk and then read the entire file
  with a File.read call. so with the change, we actually save the trip to disk.
Always print backtraces
Only rescue Omnibus:Error in the CLI
Fix a real bug that was being suppressed because of a bad rescue
Make sure deprecations are Omnibus::Errors
Fix failing health check spec (stub platform)
Remove deprecated Omnibus.configure method
Omnibus.load_configuration requires a valid filepath
Add a deprecation message for invoking Omnibus.config
Remove uses of Omnibus.config in the code
Document attr_writer for logger
Document Omnibus.ui method
Deprecate Omnibus.project_root in favor of Config.project_root
Reset Omnibus between each test
Stub the correct "Config" object
Fix broken refactor method airty
Update Omnibus.source_root API