Add support for 9.5 (use trusty image)

Here's hoping this just works?

Author: jasonmp85

.travis.yml

@@ -1,11 +1,12 @@
+sudo: required
+dist: trusty
 language: c
-
 env:
   - PGVERSION=9.1
   - PGVERSION=9.2
   - PGVERSION=9.3
   - PGVERSION=9.4
-
+  - PGVERSION=9.5
 before_script:
   - export PATH=/usr/lib/postgresql/$PGVERSION/bin:$PATH     # Add our chosen PG version to the path
   - sudo /etc/init.d/postgresql stop                         # Stop whichever version of PG that travis started
@@ -14,7 +15,6 @@ before_script:
   - sudo apt-get install postgresql-server-dev-$PGVERSION    # Required for PGXS
   - sudo apt-get install postgresql-common                   # Required for extension support files
   - createdb hll_regress                                     # Create the test database
-
 script:
   - make && sudo make install
   - psql -c "create extension hll" hll_regress