Introduce model fro OS-dependent path maps
Fix tags API: Suppress unpacking path maps

There is no unpacking code for path maps yet; trying to unpack them will
fail.
Add API for path maps schema and index
Add admin view for path maps
Minor style fixes
Log creation of new path map
Implement single path map API

Still lacking DELETE endpoint
Fix a few mistakes in docstrings
Style fix: double newline before class
Fix get on single pathmap: Transparent tags
Implement DELETE for single path maps
Add some tests for pathmap API

Not yet complete
Suppress tag_id in output after pathmap update

That column is supposed to be transparently replaced with tag.
Complete tests for pathmaps api
Fix PY2 bug: Don't use reserved name "type"
Newline at file end

[ci skip]
Merge pull request #179 from guidow/path_maps

Introduce model for OS-dependent path maps