Update travis config (add 17.0 and remove some older releases)

.travis.yml

@@ -1,9 +1,6 @@
 language: erlang
 otp_release:
-  - R16B
-  - R15B02
-  - R15B01
-  - R15B
+  - 17.0
+  - R16B03
+  - R15B03
   - R14B04
-  - R14B03
-  - R14B02