Ability to disable default H2 Indexing.

It is impossible for now to use IndexingSPI without H2Indexing due to next reasons:

• H2Indexing always starts if IgniteH2Indexing class found in classpath.
• if IndexingTypes are set and IndexingSPI is configured, then both IndexingSPI and H2Indexing is used. If IndexingTypes is not set, then both indexers are disabled.

We need to add an option that force disabling H2IndexingSpi.
It look like the only workaround for now is remove ignite-indexing jar from classpath.