[PROPOSAL] Add max_retry_count and wait kwargs to Command::Base#step

[zzaakiirr]

Why?

Command::Base#step with retry_on_failure: true option can enter infinite loop if block passed to this method returns falsey value

Example

This code enters infinite loop:

Command::Base.new(config).step("Infinite loop example", retry_on_failure: true) { false }

Proposal

1. Add max_retry_count option to prevent infinite loop
2. Add wait option so that time after which passed block should be retried can be configurable

[zzaakiirr]

Issue #157 can be addressed after this issue