Do not calculate coverage when running tests locally

Having the coverage calculation code in the test files makes it hard to debug
tests, so it is better to only analyze coverage on Travis, and not locally.

test/karma.config.js

@@ -57,13 +57,7 @@ module.exports = function(karma) {
       '/rendering/': '/base/rendering/',
       '/spec/': '/base/spec/'
     },
-    preprocessors: {
-      // source files, that you wanna generate coverage for
-      // do not include tests or libraries
-      // (these files will be instrumented by Istanbul)
-      '../src/**/*.js': ['coverage']
-    },
-    reporters: ['progress', 'coverage'],
+    reporters: ['progress'],
     coverageReporter: {
       reporters: [
         {
@@ -125,6 +119,12 @@ module.exports = function(karma) {
       browserNoActivityTimeout: 240000,
       customLaunchers: customLaunchers,
       browsers: Object.keys(customLaunchers),
+      preprocessors: {
+        // source files, that you wanna generate coverage for
+        // do not include tests or libraries
+        // (these files will be instrumented by Istanbul)
+        '../src/**/*.js': ['coverage']
+      },
       coverageReporter: {
         reporters: [
           {