Add support to hbase shell to remove coproc by its class name instead of coproc ID

The syntax for removing coproc is as below:
  hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'coprocessor$1'

We have to use coproc id to remove a coproc from a given table.

Consider the following scenario. Due to some bug in a coproc, we have to remove a given coproc from all the tables in a cluster. Every table can have different set of co-procs. For a given co-proc class, the coproc ID will not be same for all the tables in a cluster. This gets more complex if we want to remove co-proc from all the production clusters.

Instead we can pass a co-proc class name to alter table command. So if a table has that co-proc, it will remove otherwise do nothing.