refactoring: ServerBook class
Merge branch 'master' into tags-master
refactoring: introduced SimpleDialogActivity class
Merge branch 'master' into tags-master
code simplification + introduced MissingBookActivity
Merge branch 'master' into tags-master
MissingBookActivity in AndroidManifest, code cleanup
Merge branch 'master' into tags-master
fixed possible saver thread issue + code simplification
Merge branch 'master' into tags-master
hide missing book notification
Merge branch 'master' into tags-master
Urls in SyncData
Merge branch 'master' into tags-master
better missing book notification
Merge branch 'master' into tags-master
cleanup
Merge branch 'master' into tags-master
used MissingBookActivity
Merge branch 'master' into tags-master