Fixed setting column width back to undefined by setting it to -1. #7922

svn changeset:25591/svn branch:6.8

Conflicts:
	server/src/com/vaadin/ui/Table.java

Reverted change included by mistake in changeset [25591] for #7922

svn changeset:25606/svn branch:6.8

Change-Id: I6765a52ab213c131cca053227ee72b0007552f7f