Bitcoin-Qt: add Genesis blocks time for testnet

- add the Genesis blocks time for the testnet in
  ClientModel::getLastBlockDate()
small update to release-process.txt

- expand the description for updating the translations
- sort the paths/files, which need to have the version number updated, in
  alphabetical order
- use a more current version number in git tag and git shortlog
Merge pull request #2464 from Diapolo/release-process

small update to release-process.txt
Merge pull request #2460 from Diapolo/clientmodel

Bitcoin-Qt: add Genesis blocks time for testnet