Made Dublin Core property names lower-case
Made Dublin Core property names lower-case

[The Guidelines for implementing Dublin Core in XML](http://dublincore.org/documents/dc-xml-guidelines/), Section 4.2 Implementation guidelines says:

> “Recommendation 4. The property names for the 15 DC elements should be all lower-case.”
[Update:] The prefic DC needs to be all upper-case, the property name all-lowercase.
```xml
<meta name="DC.property1" content="foo" />
<meta name="DC.property2" content="foo" />
```

Dublin Core Properties are currently output in upper-case and/or a mixture of them
```xml
<meta name="DC.property1" content="foo" />
<meta name="DC.Property2" content="foo" />
```

I have changed the property names as per Dublin Core recommendation and made them all lower-case.

Signed-off-by: Stefan Gentz <14053c3744e43452334dd35f7f313e8e19b7f195@adobe.com>

drmacro/dita-ot,infotexture/dita-ot,shaneataylor/dita-ot,dita-ot/dita-ot,shaneataylor/dita-ot,dita-ot/dita-ot,infotexture/dita-ot,infotexture/dita-ot,infotexture/dita-ot,drmacro/dita-ot,drmacro/dita-ot,dita-ot/dita-ot,shaneataylor/dita-ot,drmacro/dita-ot,dita-ot/dita-ot,dita-ot/dita-ot,drmacro/dita-ot,infotexture/dita-ot,shaneataylor/dita-ot,shaneataylor/dita-ot