Update mcc icons per design.

www/img/mcc-icons/mail.svg

@@ -5,7 +5,7 @@
     <desc>Created with Sketch.</desc>
     <defs></defs>
     <g id="Page-1" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
-        <g id="-Transaction-icons" transform="translate(-139.000000, -2076.000000)" stroke-width="0.8" stroke="#FFFFFF" fill="#000000">
+        <g id="-Transaction-icons" transform="translate(-139.000000, -2076.000000)" stroke-width="0.8" stroke="#FFFFFF" fill="#9B9BAB">
             <g id="mail" transform="translate(140.000000, 2077.000000)">
                 <path d="M42.4316406,0 L1.56835938,0 C0.708984375,0 0,0.6875 0,1.56835938 L0,26.7050781 C0,27.5859375 0.708984375,28.2734375 1.56835938,28.2734375 L42.4316406,28.2734375 C43.2910156,28.2734375 44,27.5859375 44,26.7050781 L44,1.56835938 C44,0.6875 43.2910156,0 42.4316406,0 L42.4316406,0 Z M40.7128906,1.56835938 L23.1171875,19.1640625 C22.8164063,19.4648438 22.4082031,19.6367188 22,19.6367188 C21.5917969,19.6367188 21.1835938,19.4648438 20.8613281,19.1640625 L3.265625,1.56835938 L40.7128906,1.56835938 Z M42.4316406,26.2324219 L30.3359375,14.1367188 L42.4316406,2.04101562 L42.4316406,26.2324219 Z M1.56835938,2.0625 L13.6425781,14.1367188 L1.56835938,26.2109375 L1.56835938,2.0625 Z M3.265625,26.7050781 L14.7382812,15.2109375 L19.7871094,20.28125 C20.4101562,20.8828125 21.2050781,21.1835938 21.9785156,21.1835938 C22.7734375,21.1835938 23.5683594,20.8828125 24.1699219,20.28125 L29.2402344,15.2109375 L40.7128906,26.7050781 L3.265625,26.7050781 Z"></path>
             </g>