Merge pull request #4 from mintsoft/master

Adding areas and volumes
Fix square kilometer factor
Add square kilometer test
Fix km^2 to ha test
Merge pull request #6 from chrisjwilsoncom/master

Fix square kilometer factor
Merge branch 'master' of github.com:elohmrow/Convert-Pluggable

Conflicts:
	t/Convert-Pluggable.t