delete mnesia files and restart it when start fails
delete mnesia files and restart it when start fails

Change-Id: I08d78f1a649eee7d8848be3eddb4db66d4f8cae8
Reviewed-on: http://review.membase.org/6371
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Bin Cui <ed18693fff32c00e22495f4877a3b901bed09041@gmail.com>
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

daverigby/ns_server,ceejatec/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,membase/ns_server,membase/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,daverigby/ns_server,daverigby/ns_server,membase/ns_server,vzasade/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,vzasade/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,daverigby/ns_server,ceejatec/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,vzasade/ns_server,ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,ceejatec/ns_server,mschoch/ns_server,membase/ns_server,pavel-blagodov/ns_server,pavel-blagodov/ns_server,vzasade/ns_server,t3rm1n4l/ns_server