Build me a Team Communication App

Greetings, Read this carefully. I need a team communication application, where members can be invited via email, there can be file sharing ability and ability to create multiple channels along with one on one communication. It is similar to Slack but very simple in features as compared to that. Designs will be provided. The budget for this entire solution IS INR. 8000. ONLY BID IF YOU ARE READY TO WORK WITH THIS AMOUNT. We are a growing organization and cannot invest lacks as of now. BUT, BUT, THE PERSON WHO AGREES TO WORK WITH US TO BUILD THIS APP WILL BE A PART OF OUR ORGANIZATION FOREVER AND HE / SHE WOULD BE RECEIVING A SMALL SHARE OF THE INCOME WE GENERATE AND ALSO RECEIVE MORE LONG TERM PROJECTS SINCE WE ARE RAPIDLY GROWING. Having said this, we need a team communication app with the most basic features described above. Only for Android Platform. Start with 'YOW' if you have gone through else your application wont even be read.