Partners: Validation on adding multiple primary hashtags.

[manjitapandey]

Is your feature request related to a problem? Please describe.
Users can currently add multiple primary hashtags on the primary hastag field of addition or editing of partner, leading to confusion and inconsistency. This also affect the partners statistics that are loaded based on primary hashtag.

Describe the solution you'd like
This can be improved by allowing only one primary hashtag. If a user tries to add more separated by comma or space, display an error message.