include overlay files in tar
Merge pull request #223 from tsloughter/tar

include overlay files in tar
provider task dependencies
add support for rebar3 deps dir
support config passed in as proplist instead of filename
split providers out into separate shared app with rebar3
add support for pre and post provider hooks
fix tests for providers moved to new app and config list option
support only the 3 last major versions
support for running mulitple targets again
add 17.1 to travis tests