Bugfix/274 cannot add dataset to space

[tcnichol]

Description

I found that if you went to a dataset page, if you wanted to add it to a space no spaces would be returned in the dropdown due to an error. "5" was being passed in as the date in api.spacesListCanEdit instead of the limit.

To fix I only added one extra null for the Option[Date]

Review Time Estimate

• Immediately
• Within one week
• [ x] When possible

Types of changes

• [ x] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• [x ] I have updated the CHANGELOG.md.
• [ x] I have signed the CLA
• I have updated the documentation accordingly.
• [ x] I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• [ x] All new and existing tests passed.