Add travis build integration

[Kigamba]

Kindly add travis build integration to the app:

• The file will look something like this https://github.com/OpenSRP/android-p2p-sync/blob/master/.travis.yml
• The expected result is that everytime you push to a branch, the build is started on travis as you can see here

and the resulting build here https://travis-ci.org/OpenSRP/android-p2p-sync/builds/655269737?utm_source=github_status&utm_medium=notification

• I have enabled this repository on travis. You will only need to add the file & make sure the configurations are OK. You will also need to login to travis using your github account so that you can see the builds on travis here https://travis-ci.com/

@VicMB243 Kindly get back in case you face any challenges. This should be fun and a bit explorative. I already know how to set this up but the aim is for you to know what build systems are, the different kinds, why people use them since this is used in software engineering a lot

[VicMB243]

okey