Replace AndroidHttpClient with OkHttpClient

[cketti]

OkHttp has many nice features built-in and a nicer API. Check the OkHttp website for more details.

[cketti]

This also fixes issue #75.

[johnjohndoe]

@cketti I reviewed your changes and they look good to me. I am happy to merge and test them for a redeployment of this app which I will release in a few days. Can you therefore please address the following issues to enable a clean merge:

• Rebase onto current master of tuxmobil/CampFahrplan.
• Update OkHttp to the latest version in commit b3f2c29.
• Apply your build script changes of commit 8f546f1 to the camp2015 flavor as well.

Feel free to rewrite the history of your branch to produce clean commits!

[cketti]

Will do.

[johnjohndoe]

@cketti I would need it within the next 24 hours to include it. Just let me know if you have time.

[cketti]

Sorry, it's unlikely I'll find the time to do it before the weekend.

[johnjohndoe]

@cketti Would be very helpful if you can update/rebase this onto master before 11/16/15.

[johnjohndoe]

@tuxmobil I updated (latest version of OkHttp, updated configuration for camp2015 flavor) and rebased this branch onto current master: https://github.com/johnjohndoe/CampFahrplan/tree/okhttp

[tuxmobil]

Thanks. Github shows merge conflicts, though.

[tuxmobil]

done, thanks.

[johnjohndoe]

Merged here.