[SPARK-8525] [MLLIB] fix LabeledPoint parser when there is a whitespace between label and features vector

fix LabeledPoint parser when there is a whitespace between label and features vector, e.g.
(y, [x1, x2, x3])

Author: Oleksiy Dyagilev <oleksiy_dyagilev@epam.com>

Closes #6954 from fe2s/SPARK-8525 and squashes the following commits:

0755b9d [Oleksiy Dyagilev] [SPARK-8525][MLLIB] addressing comment, removing dep on commons-lang
c1abc2b [Oleksiy Dyagilev] [SPARK-8525][MLLIB] fix LabeledPoint parser when there is a whitespace on specific position