Adding 'mocha' test, errorHandlers, export modules

1. Add test powered by mocha, you need to run 'npm install -g mocha' and
then run 'mocha' in the project's root directory

2. Add 'export.js' which exports files in .csv .xlsx .xls (unfinished)

3. Add route 'exportPage.js' to support export (unfinished)

4. Add Errorhandlers in 'production' mode. We still using Express's
errorhandlers running in other modes
Merge branch 'master' of github.com:pollow/Contacts