[Issue #4] Building out test suite

Fixing exp, exp2, and copysign functions (@UsrNameu1)

Squashed commit of the following:

commit bf2839ed03e0eebf455ffe126f327f3a32523d0b
Author: Mattt Thompson <m@mattt.me>
Date:   Sat Nov 29 16:27:35 2014 -0800

    Building out test suite

commit d937a3b72366319b22a9188162599f6fc1ba2cd2
Author: UsrNameu1 <tea_room_1028@yahoo.co.jp>
Date:   Fri Oct 24 02:16:01 2014 +0900

    Modify copysign (swap sign & magnitude in function)

commit 7ffef5eab5769bff77552f631ce6a6d44f75b359
Author: UsrNameu1 <tea_room_1028@yahoo.co.jp>
Date:   Fri Oct 24 02:14:23 2014 +0900

    Add Auxiliary test (that fails)

commit c5a767a1ac584f4147867fcb8bb977ea69acb720
Author: UsrNameu1 <tea_room_1028@yahoo.co.jp>
Date:   Fri Oct 24 02:02:48 2014 +0900

    Modify exp, exp2 arguments

commit 0dfdcc0f418aa8247f8b0fade354eaecd4b7d22c
Author: UsrNameu1 <tea_room_1028@yahoo.co.jp>
Date:   Fri Oct 24 01:56:34 2014 +0900

    Add Exponential Tests