This commit enables complete keyboard accessibility for editing the block list including list navigation via cursor keys, editing via enter key and deletion via backspace. The placeholder item for adding new items is now non-removable and is indicated as such. The 'Save'-button is disabled during processing of a request. The window is closed on 'Save' if no changes have been made or the changes have been applied successfully. On failure the error message is shown in the window. A description text has been added at the top to tell the user about the use of the dialog. Test-Information: Success cases have been tested by running Swift and do change the blocking list via mouse and keyboard and doing no changes at all. Error cases have been tested using a server adjustment which replys with IQ errors on any blocklist change. Change-Id: I028a9dd15e66ba7363a30b66c5d5a15ba2a5a518