3rdParty: update boost version
tuttleHost: minor code clean on log formatters

Issue #293
sam tools: don't use log for standard console output

* We should use log for logging purposes. Printing the help has nothing to do with log.
* sam-do: The log level is now set before preloading plugins.

Issue #293
tuttleHost: don't put invalid plugins into the plugins cache

We don't want to blacklist a plugin because the load has failed once... maybe just because one guy has launch tuttle with a bad environnement (bad LD_LIBRARY_PATH).
If a plugin can't be loaded, it will not be put into the cache and we will try again at each run.

Fix #292