epedev-425

remove individual add resource button from add dataset form and use the
generic "Add Resources" button
modify LLB dataset view to show LLB challenge image and link to LLB
detail page
minor code cleanup
epedev-428

add link to dataset that links to each resource's view page
epedev-352
add text content button to LLB exploration edit view
modify dataset loading code to ignore text content
render text only content on student view
Merge pull request #31 from ooiepe/epedev-3.4-ay-epedev-352-425-428

Closes #352, 425, 428 - LLB interface updates