New fields for WriteMarker

[Sriep]

The WriteMarker sent to 0chain as part of a commit_connection transaction should contain fields for the following information

LookUpHash
Name
ContentHash

This is because Explorer needs these fields, and will read them from the WriteMarker table in the Event database.

0chain/0chain#768
0chain/0chain#733 (comment)

[Sriep]

WrtieMarkers need to be sent to 0chain when we add a new file, update a file, delete a file, copy or move a file, and rename a file.

Currently, deletes are sent as a negative size amount. I Will update as to if this is sufficient or not.