Is there a way or an app that allows me to push my latest android build to all devices that have it installed? My app is not in the Google Play market yet but would like my
You would have to build your own update mechanism into your application. It would need to periodically poll a server and ask if there was an update available. If so, it would need to download the update and trigger the installation of the update.
Maybe this is too much effort for this case.
Why don't you just use dropbox?
Install it where your developing the application then share the folder of available apks (releases) to the testers that also install dropbox on their phones. When an update occures (you move a file to the folder) they'll get an update notification, then they can go and install it right from dropbox.
I wrote an update library a while back, which you can find here. It allows you to update your app by maintaining the latest apk on a server, along with a text file with the latest version code.
The library is open source, so feel free to adapt it to your needs.
Here are some solutions you might find a few of these have forced updating and auto-updating.
Android Google Play Market - Beta Section
Appaloosa
App47
HockeyApp
For this need, I would definitely recommend TestFlight. It's free, iOS/Android compatible, and does everything expected when dealing with beta app deployment.