travis: Smaller output log

There is 4MB limit on total log size...

QubesOS/qubes-issues#1926

.travis.yml

@@ -6,6 +6,6 @@ script:
  - ~/qubes-builder/scripts/travis-build
  - travis_wait 30 make -C ~/qubes-builder iso BUILDERCONF=scripts/travis-builder.conf VERBOSE=0 COMPONENTS=installer-qubes-os
 after_script:
- - tail -n 1000 ~/qubes-builder/build-logs/installer-qubes-os-iso-*.log
+ - tail -n 100 ~/qubes-builder/build-logs/installer-qubes-os-iso-*.log
 env:
   DIST_DOM0=fc20 INSTALLER_KICKSTART=/tmp/qubes-installer/conf/travis-iso.ks USE_QUBES_REPO_VERSION=3.1