Resolved Invalid test cases for slugify

closes TryGhost#212
-Replaced invalid escape sequence with the required unicode escape sequence.

Author: keshav1sharma

packages/string/test/slugify.test.js

@@ -43,7 +43,7 @@ describe('Slugify', function () {
     });
 
     it('should remove control characters', function () {
-        var result = slugify('control:\x07notcontrol:\xB5');
+        var result = slugify('control:\x07notcontrol:\u00B5');
         result.should.equal('control-notcontrol-u');
     });
 

packages/string/test/stripInvisibleChars.test.js

@@ -9,7 +9,7 @@ describe('Strip Invisible Chars', function () {
     });
 
     it('should remove control characters', function () {
-        var result = stripInvisibleChars('control:\x07notcontrol:\xB5');
+        var result = stripInvisibleChars('control:\x07notcontrol:\u00B5');
         result.should.equal('control:notcontrol:µ');
     });