[SPARK-7940] Enforce whitespace checking for DO, TRY, CATCH, FINALLY, MATCH,...

[SPARK-7940] Enforce whitespace checking for DO, TRY, CATCH, FINALLY, MATCH, LARROW, RARROW in style checker.

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Author: Reynold Xin <rxin@databricks.com>

Closes #6491 from rxin/more-whitespace and squashes the following commits:

f6e63dc [Reynold Xin] [SPARK-7940] Enforce whitespace checking for DO, TRY, CATCH, FINALLY, MATCH, LARROW, RARROW in style checker.