[Feature] Server pagination implementation (#243)

## Major Changes
- Implement a REST style API app in epapi
- Currently implements a GET method for all entity types in the browse menu (both package level and global)
- Provides paginated results per default with query style filtering for reviewed vs unreviewed.
- Provides new paginated templates with thin wrappers per entity types for easier maintainability
- Implements e2e tests for the API

## Minor changes
- Added more comprehensive gitignore to cover coverage reports and other test/node.js etc. data.
- Add additional CI file for API tests that only gets triggered on API relevant changes.

## ⚠️ Currently only works with session-based authentication. Token based will be added in new PR.

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Co-authored-by: jebus <lorsbach@envipath.com>
Reviewed-on: enviPath/enviPy#243
Co-authored-by: Tobias O <tobias.olenyi@envipath.com>
Co-committed-by: Tobias O <tobias.olenyi@envipath.com>

epdb/logic.py

@@ -444,6 +444,7 @@ class PackageManager(object):
             if PackageManager.readable(user, p):
                 return p
             else:
+                # FIXME: use custom exception to be translatable to 403 in API
                 raise ValueError(
                     "Insufficient permissions to access Package with ID {}".format(package_id)
                 )