New Harvest Source form cleanup

[johnmartin]

Since upgrading bootstrap and the new iA changes that are now both in release-v2.0 on ckan core, the harvest source form has become a little broken.

See these:

[johnmartin]

Also needs helper text looking at.

@shevski Have any thoughts on this? It's currently:

Harvest sources allow importing metadata from other catalogues as CKAN datasets. These can be other CKAN instances or other protocols and formats.

[shevski]

I really don't know what the helper text should say. I could try and come up with some, but would appreciate some help..

[amercader]

IMO the current one is generic and nice enough. If someone complains and comes up with a better idea we can change it. If something more specific mentioning csw, etc is needed for datagov we can create a block and override it there.