Fixes post integration/deployment with aws-c-io

Fixes after doing a first deployment (#4)

* default is now the default build spec, and is valid everywhere

* Fixed dependency resolution for packages with no restrictions

* Reduced linux variations down to 2 matrices

* upload builder releases to S3

* Make run_tests actually disable CTestRun

* Simplified project resolution, should be more robust

* fixed path for script imports

* Scripts should only be loaded from newly cached project directories

* Fixed case where dir is named same as project, but doesn't contain any code, and builder tries to use it as a project

* Add useful additional variables to config