Make automatic mode default one

By default, restore operation runs with automatic off and overwrite off. This is not what user expect (point -in -time data restore).

When automatic is off, only last backup image will be restored - the image user requested. With automatic on - the whole image dependency chain will be restored, starting with the most recent full backup image, followed by incremental images. This is should be default.

When overwrite is off - we face issues similar HBASE-15862 ( Backup - delete data - restore from backup results in missing data). Overwrite is off by default.

Definitely, we need to make, at least, both modes to be default ones, at least. The question do we need these exotic modes at all? What are use case for them?

Please cast your vote, comments are welcome.

cc: tedyu, jerryhe, enis, devaraj.