[TEST] No need to test below PHP 5.6 on master

Author: polyfractal

.travis.yml

@@ -17,8 +17,6 @@ sudo: true
 php:
   - 7.0
   - 5.6
-  - 5.5
-  - 5.4
   - hhvm
 
 matrix:

README.md

@@ -90,9 +90,13 @@ eventually stop being supported.
 
 | PHP Version | Elasticsearch-PHP Branch |
 | ----------- | ------------------------ |
+| >= 5.6.0    | Dev-Master *             |
 | >= 5.4.0    | 2.0                      |
 | >= 5.3.9    | 0.4, 1.0                 |
 
+* Dev-Master only officially supports 5.6.0+, but currently runs fine on versions down to 5.4.0.  This is not, however,
+guaranteed to stay true in the future if 5.6+ features are required.
+
 Quickstart
 ----