fixes #2726 - smart class parameter override fails validation

(cherry picked from commit cfc2bb662f49d8216c2388ab35dd87af295474d0)

fixes #4234 - cannot edit host's puppet parameters

(cherry picked from commit 130f301a508ae31549145e5fa9b176f42dc20995)

fixes #4173 - don't update CR attrs when none available, taken from GH-1184

(cherry picked from commit ec4ff916ebefa8fc0d4ac41548d02407e7cf8fac)

fixes #2866 - Changing a hostgroup name doesn't update associated Smart Variable matchers

(cherry picked from commit 709ad8d6f425e0817d3faef2cc629af1458cb1c9)

fixes #3697, #3701 - more comprehensive field validations

(cherry picked from commit 4bae5cedb8ab562b6c397234c5cb1cfd604fde74)

Fixes #4032 - Use object.id for comparisons

(cherry picked from commit 409ce13e71b5a23178e109b0fb240fc2e2c6ff94)

fixes #3955 - added param_true? and snippet_if_exist template methods

(cherry picked from commit 3701a8d1c6d698ea8c57321eed2f87c74bd57728)

fixes #4023 - API v2 - compute resources partials should should attribute alias names and not database column names

(cherry picked from commit 8a0ffcfaa900079d628253ee7f9de2feec182914)

fixes #3867 - Wrong Compute Resource type shown on overview

(cherry picked from commit 2ebd2f227aef16da62c7884065bb9b47a846c9a3)

fixes #2231 - hostgroup deletion is restricted to hostgroups without children

(cherry picked from commit 8c68024ac619121312680ee8afc467857155e71d)