ISO19115 Metadata improvements

[ChrisJohnNOAA]

Description

This provides a new way to generate ISO19115 metadata for datasets. It will require enabling useSisISO19115 in setup.xml to use.

Fixes #210, #132

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

Checklist before requesting a review

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes