removing target specific meta (#299)

* updating favicon manifests

* use meta generated from target

docfiles/appmeta.html

@@ -1,16 +0,0 @@
-    <meta name="twitter:card" content="summary" />
-    <meta name="twitter:site" content="@codethemicrobit" />
-    <meta name="twitter:title" content="code the micro:bit" />
-    <meta name="twitter:description" content="Blocks+JavaScript for programming your micro:bit" />
-    <meta name="twitter:image" content="https://az851932.vo.msecnd.net/pub/drbwxcth" />
-
-    <meta property="og:title" content="micro:bit editor" />
-    <meta property="og:description" content="Blocks+JavaScript for programming your micro:bit" />
-    <meta property="og:site_name" content="code the micro:bit" />
-    <meta property="og:image" content="https://az851932.vo.msecnd.net/pub/drbwxcth" />
-    <!--
-    Canonical URL needs to wait until main release is updated.
-    <meta property="og:url" content="https://codethemicrobit.com" />
-    <meta property="og:type" content="website" />
-    <meta property="fb:app_id" content="" />
-    -->

docfiles/meta.html

@@ -1,21 +0,0 @@
-<meta name="twitter:card" content="summary" />
-<meta name="twitter:site" content="@codethemicrobit" />
-<meta name="twitter:title" content="@name@" />
-<meta name="twitter:description" content="@description@" />
-<meta name="twitter:image" content="@cardLogo@" />
-
-<meta property="og:title" content="@name@" />
-<meta property="og:site_name" content="code the micro:bit" />
-<meta property="og:description" content="@description@" />
-<meta property="og:image" content="@cardLogo@" />
-<!--
-    <meta property="og:type" content="website" />
-    <meta property="fb:app_id" content="" />
-    -->
-
-<link rel="apple-touch-icon" href="@appLogo@">
-<link rel="icon" type="image/png" href="@appLogo@">
-<link rel="mask-icon" href="https://az851932.vo.msecnd.net/pub/zwxazere/safari-pinned-tab.svg" color="#000000">
-<link rel="shortcut icon" href="@appLogo@">
-<meta name="theme-color" content="@accentColor@">
-

docfiles/target.css

@@ -1,5 +0,0 @@
-#root .avatar .avatar-image {
-    background-image: url(https://az851932.vo.msecnd.net/pub/jovrytni/microbit.simplified.svg);
-    background-size: contain;
-    background-repeat: no-repeat;
-}