Open "create env" modal if redirect_create_env_page_url not supplied

[moshe]

I came into similar issue like @gvwirth at #686 Added new condition for checking redirect_create_env_page_url

closes #686

[tuck182]

This link also appears in templates/environs/envs_landing.html. I believe the same change should be applied there.

[gvwirth]

Hi -- any updates on getting these fixes merged? We're hoping to update our Teletraan installs and it'd be great if these fixes were merged.