Frequency units

This reverts commit f35715fbb03062eda78dfcc38f9878446b5b4614.
Use units in mock.
Add units to frequency.
Voltage units

This reverts commit 78f4543b8d22fba809a9b38d4bfdcd111349fda8.
Correcting unit type to ElectricPotential
Add units to voltage in mock.
Add units to voltage.
Fix test.
Updating frequency test
Merge branch 'jburel-frequency-units' into units-length
Merge branch 'voltage' of github.com:jburel/bioformats into jburel-voltage

Conflicts:
	components/formats-api/src/loci/formats/meta/MetadataConverter.java
	components/formats-gpl/src/loci/formats/in/FluoviewReader.java
	components/formats-gpl/src/loci/formats/in/NativeND2Reader.java
	components/formats-gpl/src/loci/formats/in/NikonElementsTiffReader.java
	components/specification/src/ome/specification/XMLMockObjects.java
Merge branch 'jburel-voltage' into units-length
Power units

This reverts commit 81513eff57cdbc5da682f7079c17220827d16585.
Add units for power
Fix power unit in formats-gpl tests
Fix Formats BSD power tests