Add dimension to measurements
Add ‘at_date’ filter to measurements.
Improve v command.
Merge pull request #27 from CruGlobal/GR-56__add_dimension_to_measurements

Gr-56  add dimension to measurements
Merge pull request #29 from CruGlobal/GR-59__get_current_value_for_irregular_measurement

Add ‘at_date’ filter to measurements.
Rename category to perm_link on measurement_type

Also don’t allow non-root systems to change the perm_link once it’s set.
Allow filtering on partial perm_link

GR-57