Update travis.yml for storage testing
Adding StorageHTTP and StorageHTTPTest classes
Add new method to create new Qabel Storage Volumes

Add also a HTTPResult class, which contains the response code and a boolean,
if the request was successful.
Add a method, which tests the new function.
Add the probe method and the corresponding tests
Add upload method for blobs to the QSV
Add method to delete blobs or whole storage volumes
Change to the updated qabel storage branch
Rename file to blob
Tidy up after every test.
Remove slash from public identifier in StorageVolume.

Adding the slash in every StorageHTTP method
Change data variable to generic
Remove raw types of parameterized HTTPResult
Don't disconnect the connection in retrieve.

Otherwise is the InputStream empty.
Eliminate more raw types.
Create data folder on travis server
Set the data in retrieveBlob if the result isOk.
Create class for common synced settings
Add SyncSettingItem in Account and remove common variables
Add SyncSettingItem in DropServer and remove common variables
Add SyncSettingItem in Identity and remove common variables