Rename CSS selector names in the generated stylesheet

[yuanyan]

It helps reduce the size of the CSS that is sent down to your users.

For example, if you use BEM naming methodology:

.media{}
.media__img{}  /*Not used in current project*/
.media__img--rev{}
.media__body{}

<div class="media">
    <img src="logo.png" alt="Foo Corp logo" class="media__img--rev">
    <div class="media__body">
        <h3>Welcome to Foo Corp</h3>
        <p>Foo Corp is the best, seriously!</p>
    </div>
</div>

After run selector renaming task:

.a{}
.b{}
.c{}

<div class="a">
    <img src="logo.png" alt="Foo Corp logo" class="b">
    <div class="c">
        <h3>Welcome to Foo Corp</h3>
        <p>Foo Corp is the best, seriously!</p>
    </div>
</div>