Removed docker from travis yml as it is included in gradle build now

Author: hierynomus

.travis.yml

@@ -21,8 +21,6 @@ jdk:
 
 before_install:
   - pip install --user codecov
-  - docker build -t sshj/test-sshd ./src/test/resources/
-  - docker run -d -p 127.0.0.1:2222:22 sshj/test-sshd
 
 after_success:
 - codecov