Release version to 1.2

Features:
* Adds a counter for the comments
* Adds a badge in the comment view that counts comments / filtered comments
* Adds a guest login for speaker role

Performance improvements:
* Enables Angular Ahead-of-Time compiler
* Improves loading strategy for Service Workers

General improvements:
* Optimizes dark theme for better readability
* Only shows the toolbar for the comments when there are more than 3 comments
* Pins the searchbar for the comments to the top
* Adds ID and local time to the header component in the comment view
* Improves overall wording

Bug Fixes:
* Closes presentation view for comments on pressing ESC when in browser fullscreen
* Fixed not being able to scoll in room settings

package.json

 {
   "name": "arsnova-lite",
-  "version": "1.1.0-SNAPSHOT",
+  "version": "1.2.0",
   "license": "MIT",
   "scripts": {
     "ng": "ng",
@@ -62,7 +62,7 @@
     "karma-jasmine-html-reporter": "^0.2.2",
     "protractor": "~5.1.2",
     "ts-node": "~4.1.0",
-    "tslint": "~5.9.1",
+    "tslint": "^5.9.1",
     "typescript": "3.2.4"
   }
 }