Changes made for travis CI break up developing this gem

[wafcio]

@smcabrera a few things connected with yout changes for travis:

• .ruby-version file isn't necesary if you defined rvm section. Ruby 2.2.4 is little old, there should be defined more ruby version for travis.
• freezing bundler version in gemspec isn't so good, because with newer bundler version it is impossible to ruby bundle command. I think taht it can be achieved in different way for Travis CI

[smcabrera]

Ah thanks for pointing that out. The reason I included bundler as a dependency is that CI was failing, maybe if I use a more recent version of ruby that won't happen?

[wafcio]

Everytime freezing bundler on specific version is wrong, because each time after new bundler is released then you must update repo, which isn't good. There must be better solution.

[smcabrera]

@wafcio I think the latest commit should fix this issue.

[wafcio]

@smcabrera You added .ruby-version to .gitignore, but you didn't remove it from repo.

[smcabrera]

Ah good catch, thanks

[wafcio]

In gemspec you froze bundler version which is old right now. I tried to use old bundler version but all time it use the newest version in my system. I think it should be removed from gemspec too.