Show historic values

[Nemo64]

Since we are in git, it is technically possible to show the history of a key.
I already had a working history in backend with bitbucket using the filehistory api, but that required to download every version of the file so i dropped it for now.

Maybe an extra interface panel that loads the history on focus/demand would fit here.
This would also have to be optional, since the local filesystem has no history.