Removed IE from Travis build matrix

We still support IE 10 and 11, but the Node selenium-webdriver has
serious problems with it. Until that's fixed or worked around, IE builds
won't pass. This gets us otherwise green so we can easily see if
anything else is broken.

.travis.yml

@@ -19,14 +19,6 @@ env:
 
 matrix:
   include:
-    - env: JASMINE_BROWSER="internet explorer" SAUCE_BROWSER_VERSION=11 SAUCE_OS="Windows 8.1"
-      if: type != pull_request
-      addons:
-        sauce_connect: true
-    - env: JASMINE_BROWSER="internet explorer" SAUCE_BROWSER_VERSION=10 SAUCE_OS="Windows 8"
-      if: type != pull_request
-      addons:
-        sauce_connect: true
     - env: JASMINE_BROWSER="firefox" SAUCE_BROWSER_VERSION='' SAUCE_OS="Windows 10"
       if: type != pull_request
       addons: