refs #5940, #5923
- make read-directory ignore invalid package.json files
- display a warning about invalid package.json files on startup
- add tests to ensure read-directory continues, even with invalid package.json files
refs #5923
- add read-themes module to get a list of themes
- replace readDirectory() usage with readThemes(), where only themes are needed
- test read-themes
- test read-directory
- test validate-themes
- test parse-package-json
- add tempfile testing utility to generate temporary paths
closes#5492
- remove core/server/require-tree.js and split it into modules
- add read-directory module to recursively read directories
- add validate-themes module to scan themes and return errors/warnings
- add parse-package-json module to parse json and validate requirements
- rewrite core/server/models/index.js to manually require models
