Change form IDs for forms in steps 1 and 2
Display errors in embed forms, if any
Typo in form id fixed
Entity-type and view-mode fields made compulsory
Validate if fields from previous steps are present
Remove use of deprecated function form_get_errors
Remove use of hard-coded form_id
Merge pull request #25 from cs-shadow/form-validation

Validate form for presence of required fields