Make run_tests.sh work

Fixes:

```
$ ./run_tests.sh
./pep-it.sh: line 4: pep8: command not found
```
Merge pull request #152 from alphagov/dev-vm

Make run_tests.sh work
Remove pip install from travis file

This is now done inside run_tests.sh
Merge pull request #153 from alphagov/remove-pip-install-from-travis

Remove pip install from travis file
Default published data-set flag to off
Update tests to reflect published default to True
Merge pull request #154 from alphagov/default-published-false

Default published data-set flag to off
Add in a timestamp root schema
Get schema by file
Change tests to use a `default_schema` object

- Still a bit crufty, but less crufty than dumping the whole thing each time
Move `get_schema` into a libs/schemas

- first of many glorious schema utils functions m8
Make the schema return object a bit more obvious and descriptive
Merge pull request #155 from alphagov/jasonschemas

Add base 'timestamp' schema to datasets model
Adding in the monitoring schema

- Just `uptime`, `downtime`, and a timestamp for now
- Using the $ref feature of json schemas for timestamps, TODO: figure out how this works (inline with/open/json.load?)
Add `monitoring` as a data-type within the fixtures

- There's probably a better way of doing this, but the plan is to peg schemas to names/type keys of some kind for now
Add a simple switch to pull back various different kinds of schema

- Obviously not a sustainable model for schema sniffing, but okay for two types?
- There must be a better way to do inheritance than this, but it's good to have something to test against
Update list view tests to include monitoring

- Well chonky, but should show a switch in schema, based on data-type
require _timestamp as well
Rewrite lib/schemas to build a schema, rather than return a single one

- Chonk: Manually setting out a 'defined' list
- Loads in additional schema values then appends types to the 'allOf' property if found
Remove duplication of 'required' field in aggregated schema