fixed install_requires

fixed the problem that the vendor packages couldn't be installed
Fix bad call to superclass method
respond with 400 for _limit exceeding max_limit
gracefully handle garbage limits
broken reference test
isint util function + _skip validation + cleaner code
Merge pull request #43 from elasticsales/max-limit-tweaks

Max limit tweaks
Merge pull request #41 from wuurrd/bad_super_call

Fix bad call to superclass method
Merge pull request #36 from floqqi/patch-2

fixed install_requires
Merge branch 'master' of ssh://github.com/elasticsales/flask-mongorest into feature-mongomallard