chore(travis): enable both SauceLabs and BrowserStack

Setting env var `BROWSER_PROVIDER` to `browserstack` or `saucelabs`.

Switch to Karma with Socket.io 1.2.

karma-shared.conf.js

@@ -114,8 +114,8 @@ module.exports = function(config, specificOptions) {
     var buildLabel = 'TRAVIS #' + process.env.TRAVIS_BUILD_NUMBER + ' (' + process.env.TRAVIS_BUILD_ID + ')';
 
     config.logLevel = config.LOG_DEBUG;
-    config.captureTimeout = 0; // rely on SL/BS timeout
-    config.browserNoActivityTimeout = 60000;
+    // Karma (with socket.io 1.x) buffers by 50 and 50 tests can take a long time on IEs;-)
+    config.browserNoActivityTimeout = 90000;
 
     config.browserStack.build = buildLabel;
     config.browserStack.startTunnel = false;
@@ -131,6 +131,13 @@ module.exports = function(config, specificOptions) {
       type: 'file',
       filename: process.env.LOGS_DIR + '/' + (specificOptions.logFile || 'karma.log')
     });
+
+    if (process.env.BROWSER_PROVIDER === 'saucelabs' || !process.env.BROWSER_PROVIDER) {
+      // Allocating a browser can take pretty long (eg. if we are out of capacity and need to wait
+      // for another build to finish) and so the `captureTimeout` typically kills
+      // an in-queue-pending request, which makes no sense.
+      config.captureTimeout = 0;
+    }
   }