document links
Update sync.rst
Webhook for readthedocs.org should not be called on pull request builds.
Merge remote-tracking branch 'origin/documentation-features' into documentation-features
Moved UrlInvalidator into separate namespace
Webhook for readthedocs.org should not be called on pull request builds, fix for doc compilation pass.
Merge pull request #43 from mindaugasbarysas/documentation-features

Documentation features
doc links corrected
Merge pull request #47 from mindaugasbarysas/documentation-features

doc links corrected
Merge pull request #44 from lauriis2/feature_move-urlinvalidator-into-separate-namespace

Moved UrlInvalidator into separate namespace (Closes #36)
Renamed Pipeline's "execute" method into "start"