Issue #76 - Add parallel execution support

Fixed an issue in the Travis build

Author: ppodgorsek

.travis.yml

@@ -4,8 +4,8 @@ services:
   - docker
 
 script:
-  - docker build -t docker-robot-framework:travis . \
-      && docker run --shm-size=1g -v `pwd`/test:/opt/robotframework/tests:Z -e BROWSER=chrome docker-robot-framework:travis \
+  - docker build -t docker-robot-framework:travis .
+  - docker run --shm-size=1g -v `pwd`/test:/opt/robotframework/tests:Z -e BROWSER=chrome docker-robot-framework:travis \
       && docker run --shm-size=1g -v `pwd`/test:/opt/robotframework/tests:Z -e BROWSER=firefox docker-robot-framework:travis \
       \
       && docker run --shm-size=1g -v `pwd`/test:/opt/robotframework/tests:Z -e BROWSER=chrome -e SCREEN_COLOUR_DEPTH=8 docker-robot-framework:travis \