Spell corrections
Updated example walkthrough for release version
Documented GP id issue
Updated inference_rule typos
Merge branch 'wip-gh-pages-nested-syntax' of https://github.com/netj/deepdive into netj-wip-gh-pages-nested-syntax

Conflicts:
	doc/inference_rules.md
	doc/walkthrough.md
Merge branch 'netj-wip-gh-pages-nested-syntax' into gh-pages
Merge branch 'wip-spellcheck' of https://github.com/netj/deepdive into netj-wip-spellcheck

Conflicts:
	doc/greenplum.md
	doc/walkthrough.md
Merge branch 'netj-wip-spellcheck' into gh-pages
Using redcarpet markdown for jekyll

removing the `{% highlight ... %}` and `{% endhighlight %}`.

Use the following instead, which is compatible with Github flavored markdown:

    ```syntax
    CODE
    CODE
    ```