Make the retry strategy configurable.

The previous behaviour is kept by having the default retry amount to
be one, and the retry wait to be zero.

The configurable retry strategy allows for a backing off of retry
attempts when network conditions prevent a simple strategy from
working.
Return the error directly instead of a generalized one.
Merge pull request #8 from AeroNotix/gh-alf-make-retries-configurable

Make the retry strategy configurable.