Complete rewrite to add likes

This commit replaces the icon with a SVG and adds the possibility
to like pages too. To do this the whole structure was rewritten
which makes it in the future easier to add new functions.

icons/icon.svg

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Generator: Adobe Illustrator 19.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   version="1.1"
+   id="Layer_1"
+   x="0px"
+   y="0px"
+   viewBox="0 0 55 55"
+   xml:space="preserve"
+   sodipodi:docname="icon.svg"
+   width="55"
+   height="55"
+   inkscape:version="0.92.2 2405546, 2018-03-11"><metadata
+   id="metadata19"><rdf:RDF><cc:Work
+       rdf:about=""><dc:format>image/svg+xml</dc:format><dc:type
+         rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:title></dc:title></cc:Work></rdf:RDF></metadata><defs
+   id="defs17" /><sodipodi:namedview
+   pagecolor="#ffffff"
+   bordercolor="#666666"
+   borderopacity="1"
+   objecttolerance="10"
+   gridtolerance="10"
+   guidetolerance="10"
+   inkscape:pageopacity="0"
+   inkscape:pageshadow="2"
+   inkscape:window-width="1920"
+   inkscape:window-height="1025"
+   id="namedview15"
+   showgrid="false"
+   inkscape:zoom="8.6041667"
+   inkscape:cx="38.702179"
+   inkscape:cy="24.755448"
+   inkscape:window-x="0"
+   inkscape:window-y="27"
+   inkscape:window-maximized="1"
+   inkscape:current-layer="Layer_1" />
+<style
+   type="text/css"
+   id="style10">
+	.st0{fill:#333333;}
+</style>
+<g
+   id="XMLID_2_"
+   transform="translate(-20.455206,-19.566586)">
+	<path
+   id="XMLID_4_"
+   class="st0"
+   d="m 75.5,44.1 c 0,3.6 -1.2,6.8 -3.7,9.9 -2.5,3 -5.8,5.4 -10,7.2 -4.2,1.7 -8.8,2.6 -13.8,2.6 -1.4,0 -2.9,-0.1 -4.5,-0.2 -4.1,3.6 -8.8,6.1 -14.1,7.4 -1,0.3 -2.2,0.5 -3.5,0.7 -0.3,0 -0.7,-0.1 -0.9,-0.3 -0.2,-0.2 -0.5,-0.5 -0.5,-0.9 v 0 c -0.1,-0.1 -0.1,-0.2 0,-0.4 0.1,-0.2 0.1,-0.3 0.1,-0.3 0,0 0,-0.1 0.1,-0.3 l 0.2,-0.3 0.2,-0.3 0.2,-0.3 c 0.1,-0.2 0.5,-0.5 1,-1.1 0.5,-0.5 0.8,-0.9 1.1,-1.2 0.3,-0.3 0.5,-0.6 1,-1.2 0.4,-0.6 0.8,-1.1 1,-1.6 0.2,-0.5 0.5,-1.1 0.8,-1.8 C 30.5,61 30.8,60.2 31,59.4 27.8,57.6 25.3,55.3 23.4,52.6 21.5,49.9 20.6,47 20.6,44 c 0,-2.7 0.7,-5.2 2.2,-7.6 1.5,-2.4 3.4,-4.5 5.9,-6.3 2.5,-1.8 5.4,-3.2 8.8,-4.2 3.4,-1 7,-1.5 10.7,-1.5 5,0 9.6,0.9 13.8,2.6 4.2,1.7 7.6,4.1 10,7.2 2.3,3 3.5,6.3 3.5,9.9 z"
+   inkscape:connector-curvature="0"
+   style="fill:#333333" />
+</g>
+</svg>