[Travis] Enhance the travis.yml file.

So that we see the log file when the build fails.
Also deploy on all branches because otherwise the 'on tag'
thing does not work, and fetch tags right before deploying,
so that they are present on the slave.

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index 2f70730..dfb6c36 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,14 +32,23 @@
   - travis_retry tools/download_all.py > download.log
 
 script:
-  - ../buck/bin/buck build gerrit > buck.log
-  - ../buck/bin/buck build plugins/automerge-plugin:automerge-plugin >> buck.log
+  - buck build gerrit > buck.log
+  - buck build plugins/automerge-plugin:automerge-plugin >> buck.log
+
+after_failure:
+  - cat buck.log
+
+before_deploy:
+  - cd $TRAVIS_BUILD_DIR
+  - git fetch --tags
 
 deploy:
   provider: releases
+  skip_cleanup: true
   api_key:
     secure: Hze64QC7F5SSOVoufSIPtRWb+t6Pzzvx2kJgLtPJYUj87CKOXYzVHVqHuWsa50DPfed9knDnm5nOJawZAxleXG5VxSvBERvSyUNhjNUbDkKson1/TcCl12YM5FcyM2ocsLYe/mc59V3h9LZR2mHDqVj/incxwAIxV/MJIgu5PBg=
-  file: buck-out/gen/plugins/automerge-plugin/automerge-plugin.jar
+  file: ../../build/gerrit/buck-out/gen/plugins/automerge-plugin/automerge-plugin.jar
   on:
     repo: criteo/automerge-plugin
     tags: true
+    all_branches: true