Import EpiCollect Plus datasets. Refs #424
Unit Tests #Refs 424
Include SoundCloud template. Refs #424

This commit adds the SoundCloud template (presenter and importer) to fix
the layout in the importer section.
Docs for new EpiCollect Importer. Closes #424
Merge pull request #426 from PyBossa/issue-424-epicollect

Issue 424 epicollect
start to break down enormous function
move another if tail from distance
remove another layer of nesting, coincidentally increasing PEP8-compliance
shortcut out another nested control structure
move function out of nesting
move function out of nesting
factor out duplicate function
delete redundant boilerplate
dedupe inner function; fix indentation error
factor out duplicate function invocation
remove unduplicated comment
move generator functions out of repeated code
reindent
bring branches into greater conformity with each other
bring branches into greater conformity with each other