Implement yaml-cpp as input deck parser

[johntfoster]

As discussed in #9. I have a desire to implement yaml-cpp as an input deck parser and switch to using yaml as in the input deck format. This would only require small difference from existing *.peridigm input files, but allow for some robustness in using a standardized markup format.

[johntfoster]

@djlittl Please enable TPL_ENABLE_yaml-cpp in the Trilinos configuration for the test harness. This will activate the new YAML input deck feature and associated tests for continuous integration. This may require building yaml-cpp.