Return QNetworkReply from getRequests

This patch allows the client implementation to react to specific
getRequests, such as folder checks, etc. It allows to connect
client-specific slots to requests, catch its errors and handle them
separately.

I need this patch to be able to check more than one remote folder on the
server, and not mix up their job's signal handling.
Return QNetworkReply from remote mkdir

This patch allows the client implementation to react to specific results
of mkdir requests

I need this patch to be able to catch errors from creating remote
folders.
doc: add chapter on (soft-)branding
doc: small improvements
doc: formatting fix
Doc: formatting
Doc: Introduce chapter on Architecture, Glossary
Doc: Require sphinx todo extension
[tx-robot] updated from transifex
Show user name for connection in statusdialog

Move server version purely to tooltip.

Fixes issue #8.
Installer: Only show license on special request

GPL is a distribution license, and should thus
not be required to be accepted upon installation.
Bump version of master to 1.2pre
Doc: add troubleshooting section
Debug: fix typo
[tx-robot] updated from transifex
[tx-robot] updated from transifex
doc: wording
[tx-robot] updated from transifex
Calculate overallSyncStartup on startup.
Also compute overall status for disabled folders.