.travis.yml in fasterer-0.3.2 vs .travis.yml in fasterer-0.4.0

- old
+ new

@@ -1,9 +1,15 @@
 language: ruby
+before_install:
+  # Travis bundler versions are quite out of date and can cause install errors
+  # see: https://github.com/rubygems/rubygems/issues/1419
+  - gem update bundler
 rvm:
 - 1.9.3
 - 2.0.0
 - 2.1.7
 - 2.2.3
+- 2.3.0
+- 2.4.0
 env:
   global:
     secure: MBTxmpWCjrsNKPlOoFwJUMHze3GPMz8YCXQFQG3zJBh3WGNQnz4z91ra/1P/DClyVCxHGSFCOswxCNe4kJ2zAnPyQLqGSinXy9uDpqZQUEdaRoQbPnh4/bguZNSJ429gtTpMdDSNOgQ+Hra2EFnWwHA+rLF6ImksMsu3XGKGxGE=