Fix incorrect text in Dialogue for "When..." bricks.

changed "Delete Brick" to "Delete Script" in the context menu and "Delete this brick?" to "Delete this script?" in the ensuing dialog for "When..." bricks.

- added strings for dialogue in strings.xml

- added the setting of the strings in the BrickAdapter (onClickListener)

- refactored Tests for "When..." bricks
Merge pull request #578 from Catrobat/issue#463_2

Fix incorrect text in Dialogue for "When..." bricks.