Tidy up travis and remove unsupported php versions (#321)

* Tidy up travis and remove unsupported php versions

Everything is passing now

.travis.yml

@@ -1,14 +1,19 @@
 language: php
 
 php:
-  - 7
+  - 7.2
+  - 7.1
+  - 7.0
   - 5.6
-  - 5.5
-  - 5.4
-  - 5.3
   - hhvm
   - nightly
-  
+
+matrix:
+  fast_finish: true
+  allow_failures:
+  - php: hhvm
+  - php: nightly
+
 sudo: false
 
 install:
@@ -16,3 +21,5 @@ install:
 
 script:
   - composer test
+
+