Update travis rubies to use last versions when possible (RubyMoney#759)

* Update travis rubies use last versions when possible

* Fix patch level rubies on travis

.travis.yml

@@ -1,23 +1,24 @@
+---
 language: ruby
 sudo: false
 rvm:
   - 1.9.3
-  - 2.0.0
+  - 2.0
   - 2.1.10
-  - 2.2.9
-  - 2.3.6
-  - 2.4.3
-  - 2.5.0
-  - rbx-2
+  - 2.2.10
+  - 2.3.7
+  - 2.4.4
+  - 2.5.1
+  - rbx-3
   - jruby-9.0.5.0
-  - jruby-9.1.2.0
+  - jruby-9.1.16.0
   - ruby-head
   - jruby-head
 matrix:
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-head
-    - rvm: rbx-2
+    - rvm: rbx-3
   fast_finish: true
 before_install:
   - gem update bundler