Replace inserts in wrappers

[simkall]

This pr should fix #748

Previously the sectionRefrence.replaceReferences function only replaced sg-includes in the markup variable of the given sections. Now includes are replaced in the 'sg-wrapper' variable as well.

This test input:

// List item
//
// markup:
// <li>Item</li>
//
// Styleguide 4.0.1
li {
  color: red;
}

// List footer
//
// markup:
// <div>
//   <p>hej</p>
// </div>
//
// sg-wrapper:
// <ul>
//   <li>hop</li>
//   <sg-insert>4.0.1</sg-insert>
// </ul>
// <sg-wrapper-content/>
//
// Styleguide 4.0.2

Without the fix the styles are rendered like this:

When the contents in the sg-wrapper is replaced the same styles are rendered like this:

[varya]

Can it be one ( less from each side?

[simkall]

jsHint complains if the extra ( ) is missing

[varya]

Ah, yeah. Because it's expression inside.