Output JS Karma test coverage reports to ./cover/

Per CTI direction (see bug filing), this patch moves the JS Karma test coverage
reports to ./cover/ so they may be collected in the gate for archiving.

The two runs each have their own directory so they don't overlap/conflict.

Change-Id: I0b1536c115a516f4b6ab80b5ebab5337b308c210
Closes-Bug: 1588389

.gitignore

@@ -9,6 +9,7 @@
 .coverage*
 .noseids
 .DS_STORE
+/cover
 coverage.xml
 coverage-karma
 nosetests.xml

horizon/karma.conf.js

@@ -138,7 +138,7 @@ module.exports = function (config) {
 
     coverageReporter: {
       type: 'html',
-      dir: '../coverage-karma/'
+      dir: '../../cover/horizon'
     },
 
     // Coverage threshold values.

openstack_dashboard/karma.conf.js

@@ -184,7 +184,7 @@ module.exports = function (config) {
     // Places coverage report in HTML format in the subdirectory below.
     coverageReporter: {
       type: 'html',
-      dir: './coverage-karma/'
+      dir: '../cover/openstack_dashboard'
     },
 
     // Coverage threshold values.