added opt flags to yangpath.py for --sparse, --config-after, and --prefix-module

[bensons]

Modification of the pyang OC plugin yangpath.py to enable alternative output formats, with the following option flags:

• --sparse causes the path to be output without extra whitespace
• --config-after causes the [ro] or [rw] config flag to be placed after the path, rather than before it
• --prefix-module causes the module name to be printed at the beginning of each line instead of as a section header