tiffs with npages not dividing by pageCount will give a warning instead an error

[boazmohar]

Alternative implementation to #279
Thinking of adding a flag to fromtif() that would default to the current behavior of rising an error.
Also I am sending the warning using the warning module, I saw another way using the spark logger:

log4jLogger = sc._jvm.org.apache.log4j
LOGGER = log4jLogger.LogManager.getLogger(__name__)
LOGGER.warning("number of planes...")

@sofroniewn @freeman-lab What do you guys think?

[freeman-lab]

Why don't we forget the warning stuff, because doing warnings on the workers well is hard, and instead add a keyword argument like discard_extra that will discard extra planes instead of giving an error (as we do now). Ok if you want at the same time to use our own warnings to log the file name.

[freeman-lab]

Warnings should be done like this:

thunder/thunder/utils.py

Line 4 in 0f2e29f

logging.getLogger('thunder').warn("Operation not supported in '%s' mode" % mode)

[boazmohar]

@freeman-lab Thanks for the comments!
I think it is ready to merge.

[freeman-lab]

Excellent, looks good to me @boazmohar , merging in!