[SPARK-7328] [MLLIB] [PYSPARK] Pyspark.mllib.linalg.Vectors: Missing items

Add
1. Class methods squared_dist
3. parse
4. norm
5. numNonzeros
6. copy

I made a few vectorizations wrt squared_dist and dot as well. I have added support for SparseMatrix serialization in a separate PR (https://github.com/apache/spark/pull/5775) and plan to complete support for Matrices in another PR.

Author: MechCoder <manojkumarsivaraj334@gmail.com>

Closes #5872 from MechCoder/local_linalg_api and squashes the following commits:

a8ff1e0 [MechCoder] minor
ce3e53e [MechCoder] Add error message for parser
1bd3c04 [MechCoder] Robust parser and removed unnecessary methods
f779561 [MechCoder] [SPARK-7328] Pyspark.mllib.linalg.Vectors: Missing items