kohabug 2207 - improve indicator input in MARC editor

kohabug 2207 - improve indicator input in MARC editor

Instead of having one input field for both indicators
of a variable field, the bib and authority MARC editor
now has an input field for each indicator.  This has
two main advantages:

* it is easier to tell what the indicator values are,
  even when the first indicator is a space
* it is easier to set the first indicator to blank
  and the second indicator to non-blank.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>