Allow projects to provide their own strategy overrides
Allow projects to provide their own strategy overrides

We can't let them define their own strateiges, as the HDK's
aws_build_dcp_from_cl.sh wrapper validates -strategy, but this provides
equivalent functionality, whilst also allowing projects to easily
inherit defaults from the requested strategy.

chenm001/connectal,cambridgehackers/connectal,cambridgehackers/connectal,chenm001/connectal,cambridgehackers/connectal,cambridgehackers/connectal,cambridgehackers/connectal,chenm001/connectal,chenm001/connectal,chenm001/connectal