(React) - Header and Dropdown component (#327)

* add .DS_Store to .gitignore

* create header component

* add icons image file to the project

* add new theme variables

* insert header component into Viewer

* add web fonts

* create dropdown component

* update header styles

* import dropdown with custom list into header component

* reindent index

* Update index.html

* create json file for header menu settings

* import header menu

* header prefix

OHIFViewer-react/public/index.html

@@ -1,5 +1,6 @@
 <!doctype html>
 <html lang="en">
+
   <head>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
@@ -11,6 +12,11 @@
 
     <!-- Latest compiled and minified CSS -->
     <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
+
+    <!-- WEB FONTS -->
+    <link href="https://fonts.googleapis.com/css?family=Sanchez" rel="stylesheet">
+    <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.6.3/css/all.css" integrity="sha384-UHRtZLI+pbxtHCWp1t77Bi1L4ZtiqrqD80Kn4Z8NTSRyMA2Fd33n5dQ8lWUE00s/"
+    crossorigin="anonymous">
   </head>
 
   <body>
@@ -20,4 +26,5 @@
 
     <div id="root"></div>
   </body>
+
 </html>