docs(readme): add note about ngmin limitations

Add note about what ngmin does not minsafe

Fixes #498
Merge pull request #501 from eddiemonge/htmlOpts

feat(app): use htmlmin for smaller HTML files
Merge pull request #502 from eddiemonge/498

docs(readme): add note about ngmin limitations
chore(app): fix broken commit

Left out a change in a previous commit that affected htmlmin
adding grunt-angular-templates to the build tasks