Add restore command

[asdine]

$ genji restore -h
NAME:
   genji restore - Restore a database or a table from a file created by genji dump

USAGE:
   genji restore dumpFile dbPath

DESCRIPTION:
  The restore command can restore a database or a table from a text file.

  $ genji restore dump.sql my.db 

OPTIONS:
   --help, -h                show help (default: false)

[yaziine]

I think it should take more flags for specifying the table and the engine to use:

$ genji restore -h
NAME:
   genji restore - Restore a database or a table from a file created by genji dump

USAGE:
   genji restore [options] dumpFile dbPath

DESCRIPTION:
  The restore command can restore a database or a table from a text file.

  $ genji restore dump.sql my.db 

OPTIONS:
   --engine, -e            name of the engine to use, options are 'bolt' or 'badger'. Default to 'bolt'
   --table, -t             name of the table to restore. Default to all tables
   --help, -h              show help (default: false)

If the database at dbPath doesn't exist, it should be created given the specified engine. However, if it exists, the engine flag is ignored.

[tzzed]

I think the --table option is not usefull in this case. Restoring a table from a "dump" file seems weird. In my point of view, it will be more simplest and usefull in a .restore command.
What is the expected behavior if the dbPath exists? Should the file be overwritten?
Return an error? It currently returns error: table already exists for the CREATE query.

[asdine]

I think the --table option is not usefull in this case

Agreed

What is the expected behavior if the dbPath exists? Should the file be overwritten? Return an error? It currently returns error: table already exists for the CREATE query.

I think this is good enough, we can leave it like that