Fix makefile

- pkill won't kill the shell that's running pkill
- force kill target to always succeed (without warning message)
Use generated list of test scripts

- include the set of dependenty filenames as well, otherwise updating one of
  them wouldn't trigger a rebuild of build/test.js
Add method to retrieve <meta> tag data
Refactor Fcommand data extraction+validation

- extracted data is stored in Fcommand.extractedData
- throw all validation errors in one rather than one at a time (this is
  handy for iterative development of Fcommands in case you forget a couple
  fields as you go)
- simplifies testing
Use title instead of description in content request
Constant language for tests
Test Fcommand constructor

- the tests are purposefully brittle so that pre- and post-conditions
  can be fully tested