Deprecate useless `format` option

[nezed]

The problem:

Clickhouse understands the FORMAT statement which is accepted for both read (SELECT/DESCRIBE/SHOW/etc) and write (INSERT) kinds of queries.

That means format public option is redundant because we'll always have to parse FORMAT value from query.

For now, we have several issues related to it:

• Hard to understand what to use:
  1. ch.query('INSERT INTO table FORMAT CSV') as described in CH docs

     Has #25 bug

  2. ch.query ('INSERT INTO testTable', {format: 'CSV'}) as supported by node-clickhouse

     Not even described in readme

  3. ch.query ('INSERT INTO testTable FORMAT CSV', {format: 'CSV'}) as a panic solution

     No comments

  4. ch.query ('INSERT INTO testTable', {inputFormat: 'CSV'}) as described by node-clickhouse readme

     Not working

• We have a bug #25 : query aren't separated from data when using ch.query('INSERT INTO table FORMAT CSV') (Fix #39 )
• Our readme refers to inputFormat option, which isn't implemented.

Proposed solution:

• Mark format option as deprecated and remove it from public options later
• Improve handling of FORMAT statement
• Get rid of unimplemented inputFormat references (It useless too)

@apla are you agree with this solution? I can add deprecation warning to master, for current 1+ releases and create 2.0.0 branch with deprecation.