SettingsAccessor: Generialize error messages
SettingsAccessor: Generialize error messages

The idea is to reuse this code elsewhere, so do not talk about
.user files.

Change-Id: I5db557a2c56b1eba2527b0cad2d1bdad4818ab8e
Reviewed-by: Daniel Teske <d8a411aec9a206efedb4d45b75fe8d13f1e2b628@digia.com>

danimo/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,AltarBeastiful/qt-creator,maui-packages/qt-creator,danimo/qt-creator,maui-packages/qt-creator,colede/qtcreator,kuba1/qtcreator,colede/qtcreator,xianian/qt-creator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,kuba1/qtcreator,maui-packages/qt-creator,farseerri/git_code,kuba1/qtcreator,xianian/qt-creator,Distrotech/qtcreator,AltarBeastiful/qt-creator,kuba1/qtcreator,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,farseerri/git_code,kuba1/qtcreator,AltarBeastiful/qt-creator,xianian/qt-creator,Distrotech/qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,colede/qtcreator,kuba1/qtcreator,Distrotech/qtcreator,colede/qtcreator,farseerri/git_code,colede/qtcreator,Distrotech/qtcreator,danimo/qt-creator,amyvmiwei/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,amyvmiwei/qt-creator,farseerri/git_code,maui-packages/qt-creator,AltarBeastiful/qt-creator,Distrotech/qtcreator,colede/qtcreator,farseerri/git_code,danimo/qt-creator,danimo/qt-creator,amyvmiwei/qt-creator,danimo/qt-creator,kuba1/qtcreator,maui-packages/qt-creator,AltarBeastiful/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,AltarBeastiful/qt-creator,maui-packages/qt-creator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,Distrotech/qtcreator,maui-packages/qt-creator,colede/qtcreator,xianian/qt-creator,kuba1/qtcreator,farseerri/git_code,xianian/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,danimo/qt-creator,farseerri/git_code,AltarBeastiful/qt-creator