Make build create 2 versions of HTML5 Boilerplate

The changes from this commit will make the build script create
two different versions of HTML5 Boilerplate, one with the Apache
server configurations and one without.

The reason behind this change is to allow¹ users to choose if they
want the Apache server configs or not, and to move slowly towards
providing multiple builds of HTML5 Boilerplate that contain different
server configs.

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¹ https://github.com/h5bp/html5-boilerplate/issues/1527