userportal,webadmin: remove double slash in link

Due to some of the URI rework, the base URI has a
starting slash, but some of the code assumed it didn't
this patch adds method to get the base URI without the
leading slash.

Change-Id: Ica1ee3cce0c98dffe781b7d0e9ec5c2d667b4acd
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1026593
Signed-off-by: Alexander Wels <awels@redhat.com>