Explicitly exit with status "1" for create and drop task failures

* A non-zero exit status allows subsequent shell commands to be chained
  together such as: `rake db:reset test:prepare && rspec && cap deploy`
  (if you're feeling brave :)
* Any exceptions raised during the `create` and `drop` tasks are caught
  in order to print a "pretty" message to the user. Unfortunately doing
  so prevents rake from aborting with a non-zero exit status to the shell.
* Therefore we re-raise the exceptions after the "pretty" message and
  re-catch them in the task.
* From the task we explicitly exit with a non-zero status. This method
  was chosen (rather than just letting rake fail from the exception) so
  that the backtrace is suppressed and the output to stderr is
  unchanged.

---

## Summary
The idea is that any failing rake task should return a non-zero exit status for easy chain-able shell commands. This addresses failing `create` and `drop` tasks.

## Observation
Before this change, the result of an example chain looks something like https://gist.github.com/iamvery/6978403. Notice, the inability to drop the database doesn't prevent `db:reset` from trying the rest of its sequence. Additionally, the chained `rspec` shell command tries to do its thing (ignore the bundle error).

## Solution
After this change, the chain immediately exits with a status code "1". https://gist.github.com/iamvery/6978411. This not only prevents the task sequence from running its course, it also prevents any chained commands from executing in the shell.

## Additional Information

1. I opted to exit explicitly in the rescues so that the output format is not affected. Based on what I understand about `rake` this seems acceptable. Please advise if necessary.

2. I was hesitant to submit a PR without tests, but the test suite appears to be unaffected by this change. I believe that is due to them covering "happy paths". If additional work needs to be done, please let me know!

Thank you for entertaining my request! Let me know if I must give it more attention to make it acceptable :smile: