Curate resource list in Syllabus

- [ ] Are all the listed resources still good/valid
- [ ] Are there missing resources we should add
- [ ] Add Adam's testing examples https://github.com/awead/hydra-rspec-templates

**Compare**
http://www.rubygeek.com/getting-started
https://github.com/projecthydra/sufia/wiki/Sufia-Development-Guide
https://github.com/jeremyf/take-on-development