Running script/test fails

When I run `script/test`, I get the following error message:

```
bundler: command not found: testrb
Install missing gem executables with `bundle install`
```

This is despite a successful run of `script/bootstrap`:

```
Gem environment up-to-date
Installing hooks into /home/administrator/elastomer-client
Successfully installed hooks into /home/administrator/elastomer-client
```

_I installed Ruby 2.2.4 using **rbenv** on Ubuntu 14.04._

Has anyone encountered this error before? I have not been able to determine if it is a missing gem issue or something else. Thank you!