Release 0.19.2

[johanjanssens]

1. Cache revalidator custom header support #493

Added support for custom headers to the cache revalidator. Example: --headers.Foo=foo --headers.Bar=bar

2. Improve webservice collection #479

Added a new headers config option to easily define custom headers. For example:

---
collection:
    model: webservice
    config:
        url: http://www.example.com/api/records.json
        headers: 
            Authorization: Bearer [key]
---

3. Do not cache statically if must-revalidate #491

A page will not be cached statically if it must be revalidated. This allows to set a global cache time for the static cache and still define a different cache time per page.

3. Rename KPATH_PAGES to PAGES_SITE_ROOT #475

4. Improve static cache config #485

Fixes

• Multiple nested filter constraints Multiple nested filter constraints  #477
• Do not list cached pages if caching is not enabled Do not list cached pages if caching is not enabled #481
• Fix notices Fix notices #483