Added generic python functions to read and write yaml files.

These functions will be used to pass the arguments to puppet as hiera files.

rdYaml()
This function read yaml file and return python dictionary object

wtYaml()
This function accept python dict object, and write it to yaml file.
Optionally it may append to existing yaml file
Merge pull request #16 from hkumarmk/added_generic_yaml_functions

Added generic python functions to read and write yaml files.