repository: Place checkbox to the left of its label

In general, it is more common to have a checkbox placed to the left side
of its corresponding label. Also, all the other checkboxes in Kimchi are
placed to the left side of their labels.

Change the location of the checkbox "Repository is a mirror" so that the
control element is placed to the left side of its label.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
repository: Make checkbox clickable

A good usability feature of an HTML form is to click on an element's
label to activate the element itself. For example, when clicking on a
checkbox's label, the checkbox itself is checked, instead of requiring
the user to click on the small corresponding element.

Assign the checkbox "Repository is a mirror" to its corresponding label.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
repository: Remove full stop symbol from checkbox's label

Checkboxes' labels usually do not contain a full stop symbol at the end
of sentences.

Remove the full stop symbol from the checkbox "Repository is a mirror".

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>