Reduce gem file size by excluding test files
Reduce gem file size by excluding test files

We have a whole Rails application in our tests suite. It wastes a lot of
space for it to be into the package. Here are the gem sizes before and
after this change.

```
1.1M    web-console-2.1.1.gem
20K     web-console-2.1.2.gem
```

This should close #119.

rails/web-console,jmbejar/web-console,eileencodes/web-console,gsamokovarov/web-console,tabislick/web-console,sh19910711/web-console,tabislick/web-console,rails/web-console,tabislick/web-console,eileencodes/web-console,sh19910711/web-console,zBMNForks/web-console,gsamokovarov/web-console,rails/web-console,ryandao/web-console,tabislick/web-console,zBMNForks/web-console,jmbejar/web-console,zBMNForks/web-console,ryandao/web-console,rails/web-console,sh19910711/web-console,gsamokovarov/web-console,eileencodes/web-console,eileencodes/web-console,sh19910711/web-console,gsamokovarov/web-console,ryandao/web-console,zBMNForks/web-console,jmbejar/web-console