remove unsupported browser versions from travis

Author: mreinstein

.travis.yml

@@ -21,16 +21,10 @@ matrix:
     env: BROWSER_NAME=chrome BROWSER_VERSION=29
   - node_js: '6'
     env: BROWSER_NAME=firefox BROWSER_VERSION=latest
-  - node_js: '6'
-    env: BROWSER_NAME=opera BROWSER_VERSION=latest
   - node_js: '6'
     env: BROWSER_NAME=safari BROWSER_VERSION=latest
   - node_js: '6'
     env: BROWSER_NAME=safari BROWSER_VERSION=7
-  - node_js: '6'
-    env: BROWSER_NAME=safari BROWSER_VERSION=6
-  - node_js: '6'
-    env: BROWSER_NAME=safari BROWSER_VERSION=5
   - node_js: '6'
     env: BROWSER_NAME=ie BROWSER_VERSION=11
   - node_js: '6'