Make requirements less specific

[dereulenspiegel]

Currently I am trying to create a buildroot based firmware for the Raspberry Pi to run CraftBeerPi. What is currently causing a bit of a problem are the very specific version requirements in the requirements.txt. Buildroot already provides some of the required packages, but usually in a different (but most likely compatible) version. It would make the integration of CraftBeerPi into such embedded systems much easier if there are version ranges specified for the required packages instead of very specific versions.
Unfortunately buildroot currently does not support the creation of a virtualenv (at least to my knowledge).
It would be really nice if you would conisder this, as I believe it makes integration of CraftBeerPi into other systems (buildroot, Yocto, OpenWRT) much easier.