Adding tests against LTS astropy

Author: bsipocz

.travis.yml

@@ -45,11 +45,15 @@ matrix:
         - python: 2.7
           env: SETUP_CMD='build_sphinx -w'
 
-        # Try Astropy development version
+        # Try Astropy development and LTS version
         - python: 2.7
           env: ASTROPY_VERSION=development SETUP_CMD='test'
         - python: 3.4
           env: ASTROPY_VERSION=development SETUP_CMD='test'
+        - python: 2.7
+          env: ASTROPY_VERSION=lts SETUP_CMD='test'
+        - python: 3.4
+          env: ASTROPY_VERSION=lts SETUP_CMD='test'
 
         # Try with optional dependencies disabled
         - python: 2.7