Squashed 'core/' changes from 98f8f6e..7dacfd8

7dacfd8 Merge branch 'feature/issue192' of https://github.com/syncany/syncany into feature/issue192
bfcfd92 Decrypt encrypted settings to enable sharing
628f422 Pre/Post query callback for nested plugin (here: to fix RAID0)
fc95a20 Fix regex to match raid0/s3 plugin
12980f9 Fix TS.getField()

git-subtree-dir: core
git-subtree-split: 7dacfd8544339836e1845fd12cbe5e5466952430
Merge commit '905065693774a2452ba0347e767bd6e957bd94c4' into develop
Fixed bugs related to root folder and non-existing targets

If a user chooses to use the syncany app folder as root using "/" the
dropbox api exists with an error message.

NullPointerException when a user chooses a non-existing repo folder.