Extend DB, API to support storing contact details

Make DB schema current; extend to include contacts

- Reverse-engineer current DB on dev-censor-1 into SQL script
- Extend schema with a contacts table
- Extend requests table to store contact prefs
- Fix invalid default datetime value in queue_length table

Extend API

- Extend escape() to deal with PHP NULL correctly
- Store contact details if provided
- Add ContactLoader class to fetch contact records from DB
- Store contact preferences for a request
- Extend example-client to allow POSTing of new DB fields

Trivia

- Use vagrant image DB settings
- Ignore vagrant and vim files

Contributes to openrightsgroup/cmp-issues#6

/cc @dantheta
Resolved merge conflict (hopefully)
Merge pull request #49 from openrightsgroup/feature/email-reports

Extend DB schema and API to record contacts