only install packaging tools before deploying

.travis.yml

@@ -6,7 +6,7 @@ language: c
 
 # Make sure build dependencies are installed.
 install:
- - sudo apt-get install mono-gmcs cli-common-dev libgl1-mesa-glx libopenal1 libfreetype6 dpkg rpm nsis markdown
+ - sudo apt-get install mono-gmcs cli-common-dev libgl1-mesa-glx libopenal1 libfreetype6
 cache: apt
 
 # Run the build script
@@ -35,6 +35,7 @@ notifications:
     skip_join: true
 
 before_deploy:
+ - sudo apt-get install nsis markdown dpkg rpm
  - DOTVERSION=`echo $TRAVIS_TAG | sed "s/-/\\./g"`
  - cd packaging
  - mkdir build