Use bundler 1.16.0.preX and update rubygems to the latest
Use bundler 1.16.0.preX and update rubygems to the latest

```ruby
The latest bundler is 1.16.0.pre.3, but you are currently running 1.15.4.
To update, run `gem install bundler --pre`
```
`--force` option added to replace pre-installed bundler for ruby-head

cdinger/oracle-enhanced,cdinger/oracle-enhanced,yahonda/oracle-enhanced,rsim/oracle-enhanced,rshell/oracle-enhanced,rshell/oracle-enhanced,rsim/oracle-enhanced,yahonda/oracle-enhanced