Fixes #128

In the interests of non-collision and multiple users, favorites files are now downloaded to a path that includes the user's b32username as well as the full path to the item (storage or share).

Previously:

`https://web-dc2.spideroak.com/storage/MGSXXZ6FMVVXY/DeviceName/Users/tommy/Pictures/best-pic-evar.png`

Would have been downloaded to:

`Download/SpiderOak/.favorites/DeviceName/Users/tommy/Pictures/best-pic-evar.png`

After this change, it would be downloaded to:

`Download/SpiderOak/.favorites/MGSXXZ6FMVVXY/storage/MGSXXZ6FMVVXY /DeviceName/Users/tommy/Pictures/best-pic-evar.png`
Merge branch 'master' into issue-128-storing-b32-usernames
Merge branch 'master' into issue-128-storing-b32-usernames

Had to do some manual reconciliation, certainly because I'm handling the
pull requests out of order.

Conflicts:
	src/views/FilesView.js
Merge pull request #176 from SpiderOak/issue-128-storing-b32-usernames

Fixes #128 - non-collision and multiple users