Fix fromValue from being set to NaN

fromValue would be NaN on some small changes.
fromValue was being added as a string, not a number.
This patch solves this issue.
I haven't updated the minified version.
Undoing latest commit.
fromValue was getting appended with string

fromValue was getting appended with a string, rather than calculating
the number, resulting in fromValue having values which appeared like
so: 23.7.01245876332
Merge pull request #10 from justrhysism/master

Fixed Animation Bug