PROTON-895: Let tox handle sdist and install steps (patch from Flavio Percoco).
PROTON-895: Let tox handle sdist and install steps (patch from Flavio Percoco).

Since we're not using cmake anymore, we can let tox handle the sdist and
install steps so that everything happens within the tox venv.

RobertoMalatesta/qpid-proton,prestona/qpid-proton,Karm/qpid-proton,Karm/qpid-proton,bozzzzo/qpid-proton,wprice/qpid-proton,wprice/qpid-proton,Karm/qpid-proton,RobertoMalatesta/qpid-proton,prestona/qpid-proton,gemmellr/qpid-proton,Karm/qpid-proton,RobertoMalatesta/qpid-proton,gemmellr/qpid-proton,ChugR/qpid-proton,ssorj/qpid-proton,astitcher/qpid-proton,Azure/qpid-proton,bozzzzo/qpid-proton,clemensv/qpid-proton,apache/qpid-proton,Azure/qpid-proton,prestona/qpid-proton,bozzzzo/qpid-proton,ssorj/qpid-proton,wprice/qpid-proton,astitcher/qpid-proton,Karm/qpid-proton,Karm/qpid-proton,prestona/qpid-proton,bozzzzo/qpid-proton,Azure/qpid-proton,kgiusti/qpid-proton,bozzzzo/qpid-proton,prestona/qpid-proton,Karm/qpid-proton,kgiusti/qpid-proton,apache/qpid-proton,Karm/qpid-proton,RobertoMalatesta/qpid-proton,prestona/qpid-proton,Azure/qpid-proton,clemensv/qpid-proton,RobertoMalatesta/qpid-proton,gemmellr/qpid-proton,alanconway/qpid-proton,RobertoMalatesta/qpid-proton,apache/qpid-proton,bozzzzo/qpid-proton,wprice/qpid-proton,prestona/qpid-proton,Azure/qpid-proton,ChugR/qpid-proton,Karm/qpid-proton,kgiusti/qpid-proton,gemmellr/qpid-proton-j,clemensv/qpid-proton,clemensv/qpid-proton,apache/qpid-proton,RobertoMalatesta/qpid-proton,Azure/qpid-proton,alanconway/qpid-proton,prestona/qpid-proton,wprice/qpid-proton,ChugR/qpid-proton,kgiusti/qpid-proton,alanconway/qpid-proton,clemensv/qpid-proton,Azure/qpid-proton,wprice/qpid-proton,apache/qpid-proton,bozzzzo/qpid-proton,wprice/qpid-proton,astitcher/qpid-proton,clemensv/qpid-proton,kgiusti/qpid-proton,ssorj/qpid-proton,Azure/qpid-proton,ssorj/qpid-proton,bozzzzo/qpid-proton,clemensv/qpid-proton,astitcher/qpid-proton,alanconway/qpid-proton,apache/qpid-proton,ChugR/qpid-proton,wprice/qpid-proton,clemensv/qpid-proton,wprice/qpid-proton,clemensv/qpid-proton,ChugR/qpid-proton,ssorj/qpid-proton,gemmellr/qpid-proton-j,ssorj/qpid-proton,Azure/qpid-proton,clemensv/qpid-proton,Azure/qpid-proton,prestona/qpid-proton,Karm/qpid-proton,alanconway/qpid-proton,gemmellr/qpid-proton,wprice/qpid-proton,RobertoMalatesta/qpid-proton,Karm/qpid-proton,RobertoMalatesta/qpid-proton,prestona/qpid-proton,bozzzzo/qpid-proton,astitcher/qpid-proton,kgiusti/qpid-proton,wprice/qpid-proton,gemmellr/qpid-proton,Karm/qpid-proton,prestona/qpid-proton,clemensv/qpid-proton,RobertoMalatesta/qpid-proton,Azure/qpid-proton,astitcher/qpid-proton,bozzzzo/qpid-proton,RobertoMalatesta/qpid-proton,gemmellr/qpid-proton,bozzzzo/qpid-proton,alanconway/qpid-proton,prestona/qpid-proton,ChugR/qpid-proton