fix blog post

- fix front matter
- give it today's date so it shows up as newer than the 2.12.1
  announcemnt

Author: SethTisue

blog/_posts/2016-12-05-implicit-function-types.md renamed to blog/_posts/2016-12-07-implicit-function-types.md

@@ -1,8 +1,8 @@
 ---
 layout: blog
+post-type: blog
 title: Implicit Function Types
-author: Martin Odersky
-authorImg: /images/martin.jpg
+by: Martin Odersky
 ---
 
 I just made the [first pull request](https://github.com/lampepfl/dotty/pull/1775) to add _implicit function types_ to