Merge pull request #579 from CrazyJvm/patch-1.

"in the source DStream" rather than "int the source DStream"

"flatMap is a one-to-many DStream operation that creates a new DStream by generating multiple new records from each record int the source DStream."

Author: Chen Chao <crazyjvm@gmail.com>

Closes #579 and squashes the following commits:

4abcae3 [Chen Chao] in the source DStream