Add unit tests

[vyo]

tests

swagger

• [x] availability
• [x] response type (json)
• [x] basic spec attributes (swagger version)
• [x] completeness (endpoints)
• [x] spec contents sanity check

---

solr

• [x] basic query
• [ ] page option
• [ ] rows option
• [ ] sort option
• [ ] rangeFilter option
• [x] matchFilter option
• [ ] restrict option
• [ ] groupBy option
• [ ] timeout option

---

admin

• [ ] endpoints test stubs

[vyo]

• added unit tests for swagger availability, response type and basic attributes
• refactored cli argument setup to not trigger on tests (via NODE_ENV)
• refactored logging level setup to distinguish between development, testing and production
• refactored endpoint registration to load up endpoints registered in extra modules

[vyo]

• added test command to package.json
• added coverage analysis and html report generation