feat(config): Option to exclude test for specific capability

Add the option to exclude spec files for a specific capability.
This way you can ignore spec files for one capability only.
For example if the test is known to fail in the capability.

Closes angular#1230

docs/referenceConf.js

@@ -109,7 +109,10 @@ exports.config = {
     maxInstances: 1,
 
     // Additional spec files to be run on this capability only.
-    specs: ['spec/chromeOnlySpec.js']
+    specs: ['spec/chromeOnlySpec.js'],
+
+    //Exclude spec files for this capability.
+    exclude: ['spec/doNotRunInChromeSpec.js']
   },
 
   // If you would like to run more than one instance of WebDriver on the same

lib/taskScheduler.js

@@ -55,6 +55,14 @@ var TaskScheduler = function(config) {
       capabilitySpecs = capabilitySpecs.concat(capabilitySpecificSpecs);
     }
 
+    if(capability.exclude) {
+      var capabilitySpecExcludes = ConfigParser.resolveFilePatterns(
+          capability.exclude, true, config.configDir);
+      capabilitySpecs = ConfigParser.resolveFilePatterns(
+          capabilitySpecs).filter(function (path) {
+              return capabilitySpecExcludes.indexOf(path) < 0;
+          });
+    }
     var specLists = [];
     // If we shard, we return an array of one element arrays, each containing 
     // the spec file. If we don't shard, we return an one element array