Fix HelloMessageFactory - repair handling message with bad HelloElementType
    - when message has bad HelloElementType empty list of elements will return
    - modifying test to follow fix HelloMessageFactory
    - add test for message with padding

Change-Id: Ie6a97f79a4d133b9da07b15023cda60ba74eec2f
Signed-off-by: Marian Adamjak <marian.adamjak@pantheon.sk>