pgAdmin 4 commit: Changed the Unique Columns of the Variable Control ba

Changed the Unique Columns of the Variable Control based on the input
from the user.

i.e.
Set the uniqueCol as ['name', 'role'] in case of hasRole is set to true
in schema for it, ['name', ['database'] in case of hasDatabase is set to
true, otherwise ['name'].

Also - fixed a typo in the callback function headerDataChanged(..).

Branch
------
master

Details
-------
http://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=c421bef0d09b27dabbbfd5d6e669777e79b49695
Author: Harshal Dhumal <harshal.dhumal@enterprisedb.com>

Modified Files
--------------
.../server_groups/servers/static/js/variable.js    | 31 +++++++++++++---------
1 file changed, 19 insertions(+), 12 deletions(-)