There is nothing app like that. I tried create some, but without success, even start activity from another activity in landscape mode is not possible i think (please correct me, if you know how - I would like to finish tool for starting aplications in landscape mode), but still you can modify your apk.
1) download ApkTool code.google.com/p/android-apktool
2) download your apk application file (I tried on opera mini)
3) use apktool d your.apk apksource
4) edit AndroidManifest file : only add to activity android:screenOrientation="landscape"
5) use apktool b apksource your_modified.apk
6) then the hard part sign it with these steps or some others londatiga.net/it/how-to-sign-apk-zip-files/
7) use adb install your_signed.apk and thats it