Lock RSpec version in 2.x
Rewrite RSpec syntax using transpec
Move `let` variable to `after :each` hook

```
DEPRECATION: let declaration `template_file` accessed in an `after(:all)`
```
Remove `debug` option

`config.debug` is removed at RSpec 3.0.0
* https://github.com/rspec/rspec-core/releases/tag/v3.0.0.beta1

But we can use `--debug` option instead it.
Upgrade RSpec version to 3.x
Merge pull request #64 from tricknotes/update-rspec

Update RSpec version to 3.x