make current use available to pre/post save events
Merge pull request #514 from JohnnyEstilles/feature/adding-current-user-in-pre-post-save

Adding current user available to pre/post save hooks
Changing _user to _req_user for #514
added testing ._req_user in pre/post save hooks
added mongodb service to travis-ci
Merge pull request #515 from JohnnyEstilles/feature/testing-current-user-in-pre-post-save

Adding unit test for "current user in pre/post save hooks" feature
Merge remote-tracking branch 'upstream/master'
Fix for Azure upload error
Fix Spacing
Merge pull request #519 from manuelnelson/master

Fix Azure File Upload Error
added; "track" option plugin to list
changed; "standard meta" pattern now enables list "track" option
added; "standard meta" pattern displays deprecation warning
added; unit test for list "track" option
added; helper functions for commonly used code
changed; _req_user.test to use helper functions
added; "track" option documentation to Keystone docs
formatting/phrasing changes to 'track' doc
phrasing changes to deprecation warning message (to match docs)
Merge pull request #523 from JohnnyEstilles/feature/adding-list-track-option

Adding List 'track' option (replaces #490)
Fixed link to dotenv project
Merge pull request #524 from mahnunchik/patch-1

Fixed link to dotenv project
Fixes #497