implemented webview instead of browser intent

this reverts #485, fixes #451
some minor refactoring regarding urls done too
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 #577 from Catrobat/webViewImplentation

implemented webview ready for merge
Merge pull request #578 from Catrobat/issue#463_2

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

also autoformatted catroid/AndroidManifest.xml
done
Merge pull request #580 from Catrobat/addAndrToVersion

Add Andr. to version in AboutDialog
added check for Andr. prefix at version in AboutDialogTest
Merge pull request #579 from Catrobat/fixWebViewTests

fix WebViewActivityTest
Merge pull request #582 from Catrobat/addAboutDialogTestCheckAndrPrefix

added check for Andr. prefix at version in AboutDialogTest
redesigned login dialog
fixed nullpointers in registration & login dialog