change name of files which pass rspec regression test

This PR is related to #2174. This change adds *_spec* to name of files which pass rspec regression test.

### Rake task
```
jruby bin/rake spec:regression
```
### Results
Before; on master(5041f5c)
```
288 examples, 0 failures
```
After; on master(fdc5a0e)
```
300 examples, 0 failures
```