Update .travis.yml to remove incompatible Ruby versions.
Update .travis.yml to remove incompatible Ruby versions.

Httparty requires Ruby version >= 1.9.3 so I don't think this is really useful to include below versions in Travis conf.


Bonus point this "a bit" clearer.
iKala/pushmeup,Promptus/pushmeup,ericraio/pushmeup,sdogruyol/pushmeup,estum/pushmeup,NicosKaralis/pushmeup,maxprig/pushmeup,AylaNetworks/pushmeup,jrbeck/pushmeup