Bitcoin-Qt: updates to addressbookpage

- use labelExplanation for sending and receiving tab and move the string
  from the ui-file to the source
- ensure that the table holding the label and address is resized so that
  the address column fits the address and the label column is stretched to
  fit the window size
- rename some stuff for much easier readbility in the code (I find it hard
  to get the meaning of stuff like labels or buttons)
Bitcoin-Qt: use $$TRANSLATIONS in bitcoin-qt.pro

- instead of parsing the project file by using $$_PRO_FILE_ just use
  $$TRANSLATIONS, which contains a list of all needed files, to build
  our *.qm translation files
remove proprietary psd file mentioning from assets-sttribution.txt

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>
Merge pull request #2465 from jonasschnelli/master

update assets-sttribution.txt (-psd file +svg file)
Merge pull request #2443 from Diapolo/Qt_addrbook

Bitcoin-Qt: updates to addressbookpage
small indentation, space, formatting fixes (no code changes)
Merge pull request #2456 from Diapolo/code-layout

small indentation, space, formatting fixes (no code changes)
Merge pull request #2459 from Diapolo/pro-file

Bitcoin-Qt: use $$TRANSLATIONS in bitcoin-qt.pro