Initial leveldb stress test

Just logs messages to the database as they are received.
When receiving full rate ISOBUS, the process did *not* max out.
Added opcode support from ISOBlue to Android

Before only command from Android to ISOBlue used opcodes.
First attempt at being able to get past data
Fix bug in with processing consecutive commands

The function would return after finishing the first, leaving any others
in the buffer indefinitely.
Add past data testing to `isoblue_dummy`
Past data kinda works

Need to change code for deciding when to send it.
Fix iteration by key

* comparison of keys was incorrect
* check for iterator completion incorrect
Rearrange messages to easily work with libISOBlue
Add support for delay between `can_stress` sends

Only works when sending on a single CAN interface.
Fix a bug with frame count option for `can_stress`

It usually sent far fewer than specified.
Fix some buffered data coming as new data
Merge pull request #12 from awlayton/leveldb

Leveldb