Try postgresql installation the travis way (using addons)

See http://blog.travis-ci.com/2013-11-29-postgresql-92-93-now-available/

.travis.yml

@@ -1,13 +1,10 @@
 language: c
 
+addons:
+  postgresql: 9.3
+
 before_install:
-  - lsb_release -a
-  - sudo apt-get purge postgresql-9.1 postgresql-9.2
-  - sudo apt-get install -q postgresql-server-dev-9.3
   - sudo apt-get install -q postgresql-9.3-postgis-2.1
-  - sudo apt-get install -q postgresql-9.3
-  - sudo apt-cache search postgresql | grep 9.3
-  - dpkg -l | grep postgresql
   - # Install schema_triggers
   - hg clone https://bitbucket.org/malloclabs/pg_schema_triggers &&
     cd pg_schema_triggers && make && sudo make install && cd -