Fix Rollout UI performance. (#485)

* Fix Rollout UI performance.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Remove unused column definition.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Hidden columns static.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Optimized column width for readibility.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* catch IllegalArgumentException in case directory does not exists (#487)

Signed-off-by: Michael Hirsch <michael.hirsch@bosch-si.com>

* Remove unused column definition.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Hidden columns static.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Optimized column width for readibility.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

hawkbit-ui/src/main/resources/messages.properties

@@ -483,7 +483,7 @@ header.assigned.ds = Assigned DS
 header.installed.ds = Installed DS
 header.target.status = Status
 header.target.tags = Tags
-header.total.targets = Total targets 
+header.total.targets = Targets 
 header.key = Key
 header.value = Value
 header.auto.assignment.ds = Auto assignment
@@ -505,7 +505,7 @@ label.no = No
 
 #rollout - start
 header.distributionset = Distribution set
-header.numberofgroups = No. of groups
+header.numberofgroups = Groups
 header.detail.status = Detail status
 
 header.rolloutgroup.installed.percentage = % Finished