SPARK-364 overwrite to keep collection options

[VVBondarenko]

added way to configure collection truncate approach in overwrite writing mode.

new write option: truncate_mode might have one of the following options:

• DROP same as before. Just drop collection and create new one with default configuration
• DELETE_ALL expensive delete all query. Keeps original collection, but slowly deletes all documents from it
• RECREATE saves previous options and indexes, drops the collection, creates new collection with the same options and indexes