cleaned up job_create
fixed job_creation sample
renamed/fixed read_buffer

Added dropping the leading \r\n in read_buffer and changed the name to reflect
that. The implementation is not very efficient as of yet so there's still more
work to be done.
added multiple job reserves to job_create
removed async.std dep in beanstalk.ml
conn based on throttle
updated async to use throttle where needed
made conn abstract
unexposed some functions
changed old code to allow for simultaneous jobs
updated job creation test code to throttle changes