[v.3.4-pre15] Creation of new layer fails

[mmacata]

Current Behaviour:
When creating a new layer in the menu 'map layers' - 'layers' - 'Create new' and typing in an Identifier an error occurs when clicking 'create new' for the following types: Coverage, Tile, RemoteWMS, Feature
The error message is:
j_idt78:j_idt87: Validation Error: Value is not valid

When I type in a different Identifier a different error occurs:
java.lang.NullPointerException

For the type 'GdalLayerStoreProvider' the java.lang.NullPointerException-Error occurs immediately

Expected Behavour:
When creating a new layer I can start editing the xml resource or a specific error message appears

Tested with Firefox (v.31.0) in Ubuntu 12.04

[vog]

Duplicate of #343.

[stephanr]

Resolved by #474