Fixed HTML to validate, closes PR #286

This is a squashed commit of the following:

commit 2fc4368f68d149b5e27fb6a12d5f6a173ad8f135
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 01:09:09 2013 +0530

    Indentation or prefix in index.html resolved

commit f937378dbe8d993cb3ab464be761cf6e69ddb937
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 01:04:26 2013 +0530

    spec/index.php Validated

commit 7f22d274eb2c3cd82d5b1f539380de0e0511672a
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 00:58:10 2013 +0530

    requirements/index.php Validated

commit 21a7e5c0262df4128791de0568b9748199179180
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 00:53:06 2013 +0530

    primer/index.php Validated

commit 6a2cc2d6fc7570c2667f109dd8d85ae28df4722f
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 00:38:04 2013 +0530

    /playground/index.html Validated

commit 12d9a68965c90fcf1888b941f464cf2e83d126ce
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Sat Jul 20 00:26:20 2013 +0530

    /images/index.html Validated

commit ad00c5a3169fec031936f50cc08b9c33e4e12664
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Fri Jul 19 23:48:39 2013 +0530

    Validated learn.html

commit 0d1fee5352b5d553024aca865b296f1a5ee48279
Author: Vikash Agrawal <vikashagrawal1990@gmail.com>
Date:   Fri Jul 19 23:37:33 2013 +0530

    index.html validated