Need to synchronize `watch()` and `watchCh()` methods

[lucifercr07]

• In current implementation there can be race conditions for both the methods if client object is shared between go-routines.
• Even if client object is segregated race conditions can occur since WatchCh() method starts a separate go-routine that runs watch(). If the main go-routine calls Close() while watch() is running this can cause panic.
• Also need to look at creation of client, it looks like it doesn't handshake with .WATCH rather with command, might need to fix.

[mintobit]

Working on this