* Generate meta elements from useful front matters.
Limited to the default template and specific elements.
* Rerun gofmt
* Add "keywords" and remove "language" to/from the list of meta tags.
* Add a simple positive list test for the meta tag generation.
* Move the meta tag list to a var at the begin of the file.
Seperate the Meta tags from the other front matters:
- Don't override user settings with name `meta`
- Cleaner Code.
* Remove the uneccessary `[:]` in the []Bytes to String casting.
@mholt was right ;)
* One minor refinement. Combining two statements.
