Update coverage configuration and reporting settings

- Added 'manage.py' and 'evalai/wsgi.py' to the .coveragerc omit list to exclude them from coverage reports.
- Modified karma.conf.js to adjust the lcovonly reporter configuration for better output structure.

.coveragerc

@@ -16,8 +16,9 @@ omit =
     scripts/seed.py
     node_modules/
     bower_components/
+    manage.py
+    evalai/wsgi.py
 source = evalai/
-data_file = .coverage
 
 [report]
 exclude_lines =

karma.conf.js

@@ -92,7 +92,7 @@ module.exports = function(config) {
         includeAllSources: true,
         dir: 'coverage/frontend/',
         reporters: [
-            { type: "lcovonly", file: "lcov.info" },
+            { type: 'lcovonly', subdir: '.', file: 'lcov.info' },
             { type: 'text-summary' }
         ]
     }