Update README.md
Consolidate source files
Enable `github` and `table` showdown extensions.
Ignore language-specified code blocks. Closes #9
Build both unminified and minified versions at the same time.
Disable Sqwish strict mode. Fixes #14
Some less sucky styles.
Include patched table extension.

This version from coreyti/showdown#48 fixes having multiple tables in the same document. Included in the command until it gets merged into Showdown.