Improve error messaging when unable to find @Package

Fixes #6

Author: matthewp

.editorconfig

@@ -0,0 +1,9 @@
+; Unix-style newlines
+[*]
+end_of_line = LF
+indent_style = tab
+indent_size = 4
+
+[{*.json,*.yml,*.md}]
+indent_style = space
+indent_size = 2

package.js

@@ -4,40 +4,53 @@ var fs = require("graceful-fs");
 /**
  * @parent bit-docs-tag-package/tags
  * @module {bit-docs-process-tags/types/tag} bit-docs-tag-package/tags/package @package
- * 
+ *
  * @description Adds the package's `package.json` info to the
  * [bit-docs/types/docObject].
- * 
+ *
  * @signature `@package PATH`
- * 
+ *
  * Once added to the [bit-docs/types/docObject], you can reference the
  * `package.json` properties like `name`, `description`, `author`, etc in
  * `.mustache` templates.
- * 
+ *
  * @param {String} PATH The path to a `package.json` file.
- * 
+ *
  * @body
- * 
+ *
  * An example `package.json` file might look like:
- * 
+ *
  * ```js
  * {
  *   "name": "my-package",
  *   "version": "0.0.1",
  *   "description": "My cool package.",
  * }
  * ```
- * 
+ *
  * That gets used like:
- * 
+ *
  * ```js
  * @@package ./demos/package.json
  * ```
  */
 module.exports = {
     add: function(line, curData, scope, objects, currentWrite) {
-        var pkgPath = path.join(path.dirname(this.src.path), line.replace("@package", "").trim());
-        var pkg = fs.readFileSync(pkgPath).toString();
+		var atPackagePath = line.replace("@package", "").trim();
+		var pkgPath = path.join(path.dirname(this.src.path), atPackagePath);
+		var pkg;
+		try {
+			pkg = fs.readFileSync(pkgPath).toString();
+		} catch(e) {
+			if(e.code === "ENOENT") {
+				var newError = new Error('@package: Unable to locate ' +
+					atPackagePath + " from " + this.src.path
+				);
+				throw newError;
+			}
+
+			throw e;
+		}
         var result = JSON.parse(pkg);
 
         // delete things that would be too big