changed the documentation to reflect the way the URI's are supposed to look
Fix #1317
Merge pull request #2417 from LearnBoost/gh-2414

changed the warning that is given when a MONGOOSE_SET_TEST_URI is not set
fix #2434 remove side effect of #1638
Merge pull request #2436 from liukun/gh-2434

fix #2434 remove side effect of #1638 for 3.8.x
Test coverage for #1898
release 3.8.19
now working on 3.8.20
took out hyperlinks for boolean, array, and mixed because there is not substantial documentation
Merge pull request #2455 from LearnBoost/gh-2444

gh-2444 took out hyperlinks for boolean, array, and mixed because there is not substantial docs