Coerce text to string.

Caused issues with numbers being .replace()'d.

INSTALL.md

@@ -19,7 +19,7 @@ npm install gh-badges
 ```js
 var badge = require('gh-badges');
 badge({ text: [ "build", "passed" ], colorscheme: "green" },
-  function(svg) {
+  function(svg, err) {
     // svg is a String… of your badge.
   });
 ```

badge.js

@@ -52,6 +52,10 @@ function makeImage(data, cb) {
   if (!(data.template + '-' + data.format in templates)) {
     data.template = 'default';
   }
+  // String coercion.
+  data.text[0] = '' + data.text[0];
+  data.text[1] = '' + data.text[1];
+
   var template = templates[data.template + '-' + data.format];
   if (data.colorscheme) {
     data.colorA = colorscheme[data.colorscheme].colorA;
@@ -63,7 +67,12 @@ function makeImage(data, cb) {
   ];
 
   addEscapers(data);
-  var result = template(data);
+  try {
+    var result = template(data);
+  } catch(e) {
+    cb('', e);
+    return;
+  }
 
   if (data.format === 'json') {
     cb(result);