Add theme-color support to header

The color is controlled by the site parameter `themeColor` (defined in
config.toml). theme-color support allows us to better display the team
color.

See https://developers.google.com/web/updates/2014/11/Support-for-theme-color-in-Chrome-39-for-Android?hl=en


for more information.

Closes #4.
Signed-off-by: Ethan Madison <ethan@ethanmad.com>

layouts/partials/header.html

@@ -8,6 +8,9 @@
 		<link rel="alternate" href="/index.xml" type="application/rss+xml" title="{{ .Site.Title }}">
 		<link rel="icon" href="{{ $baseUrl }}/favicon.ico">
 		<title>{{ .Title }}{{ if eq $isHomePage false }} - {{ .Site.Title }}{{ end }}</title>
+        {{ with .Site.Params.themeColor }}
+        <meta name="theme-color" content="{{ . }}" />
+        {{ end }}
 		<!--<link href="http://fonts.googleapis.com/css?family=PT+Sans:400,700" rel="stylesheet" type="text/css">-->
 		<link rel="stylesheet" href="{{ $baseUrl }}/css/highlight/{{ if isset .Site.Params "highlightStyle" }}{{ .Site.Params.highlightStyle }}{{ else }}default{{ end }}.css">
 		<link rel="stylesheet" href="{{ $baseUrl }}/css/bootstrap.min.css">