Merge pull request #2948 from hypothesis/BPA1eZ9O-add-developer-api-tokens

Add developer API tokens

h/static/styles/api-token-input.scss

+.api-token-input {
+  width: 100%;
+  line-height: 3em;
+  text-align: center;
+}

h/static/styles/app.scss

@@ -9,6 +9,7 @@ $base-line-height: 20px;
 @import './common';
 
 // components
+@import './api-token-input';
 @import './excerpt';
 @import './primary-action-btn';
 @import './dropdown-menu-btn';