Some code tweaks to post/osx/mount_share.

* Make PROTOCOL an Enum
* Move path override options to advanced section
* More Enumerable rework
* Move one-off regexes back to inline, pull out protocol list
More tweaks to mount_share.

* Adds some docs to some of the methods to further distinguish
the separate sets of shares.
Change the Recent shares implementation.

* Allows us to see protocol of Recent Shares
* Parses protocol from file share URL
DRY up URL_REGEX constant.
Merge pull request #1 from jvennix-r7/review_osx_mount_pr

Tweaks & fixes to osx mount PR