Cannot add children to direct containers

[scossu]

Environment

Operating system: Various

Python version: N/A

LAKEsuperior release, branch, or commit #: 1.0.0a13

Steps to reproduce

Create a direct container with PUT (currently POST is unavailable due to #56) and attempt to insert child resources.

Observed behavior

(from @acoburn 's post)

Once the direct container is successfully created, I am unable to create child resources in it (neither via PUT or POST). This is the response:

"The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application."

But there is nothing in any of the logs, other than these lines in the access log:

127.0.0.1 - - [13/Apr/2018:11:24:50 -0400] "POST /ldp/dc4 HTTP/1.1" 500 291 "-" "curl/7.54.0"
127.0.0.1 - - [13/Apr/2018:11:35:11 -0400] "PUT /ldp/dc4/child1 HTTP/1.1" 500 291 "-" "curl/7.54.0"

Expected behavior

Resources should be created under the container with the correct relationships.

Other notes worth mentioning

Indirect containers might exhibit similar behavior. Needs testing.

[scossu]

Fixed in #58