Merge pull request #22 from nuft/master

Boot code, config update, read flash...
config_write(): pass config by reference.
Add config write to flash command.
Fix types.
client: complete bootloader commands.
Temp fix for host build
Add tests for boot to application
Fix datagram commands tests
Fix integration tests
Fix string compare in flash writer test.
Fix and complete config test.
Correct MessagePack map size.
Add memory layout abstraction to simplify testing.
Implement Travis build script (fix #31)
Use HTTPS for submodule

If we use SSH, Travis CI is not able to clone the submodule repository.
Remove tagged struct init

For some reason, Travis CI's gcc doesn't like tagged structure init in
cpp files.
Merge pull request #28 from antoinealb/fix-unit-tests

Fix unit tests
Add Travis CI badge
Correct block_crc usage.
Change types to be compatible with msgpack python.