Add functions for new Bioactivity endpoints

[rachmaninoffpk]

There are new endpoints in Bioactivity, focused on Assay information. Build functions to wrap these new endpoints.

[madison-feshuk]

Bioactivity endpoints:

CTX Bioactivity API Resource/Endpoint	ctxR Status
Bioactivity Assay Resource	--
GET: Get annotation by aeid	get_annotation_by_aeid()
GET: Get all assays	get_all_assays(). Updates needed as described in #62
Bioactivity Data Resource	--
GET: Get summary by aeid	get_bioactivity_summary()
GET: Get data by spid	get_bioactivity_details()
GET: Get data by m4id	Additional parameters in above function
GET: Get data by dtxsid	Additional parameters in above function
GET: Get data by aeid	Additional parameters in above function
Assay Source Resource	--
GET: Search by starting value	NEW function needed
GET: Search by exact value	NEW function needed
GET: Search by substring value	NEW function needed
Bioactivity Model Resource	--
GET: Get toxcast model by dtxsid	NEW function needed
GET: Get toxcast model by dtxsid and model	Additional parameters in above function
Analytical QC Resource
GET: Get analytical QC data by DTXSID	NEW function needed
Bioactivity AOP Data Resource
GET: Get aop data by toxcast aeid	NEW function needed
GET: Get aop data by event number	Additional parameters in above function
GET: Get aop data by entrez gene id	Additional parameters in above function