Use sentry protocol v4 instead of v2 ; send tags and an 'extra' dictionary with the events

`tags` parameter: I picked up #18 and #20 and refactored the code to be retro-compatible. (so auto tagging of the build version, OS and device model)

`extra` parameter: I moved the stacktrace from the extra key to the `stacktrace` sentry module which leave available the `extra` parameter for custom data (user id, …).

using this version on a real project with no problem, all test are passing :)

Arthur