test: initial list of flaky tests

This poplulates the lists of flaky tests with tests that failed recently
in Jenkins.

PR-URL: nodejs#2424

2015-08-25 io.js v3.2.0 Release

2015-08-19 io.js v3.1.0 Release

2015-08-04 io.js v3.0.0 Release

2015-08-03 io.js v3.0.0 RC 7

2015-07-30 io.js v3.0.0 RC 6

2015-07-28 io.js v2.5.0 Release

2015-07-24 io.js v3.0.0 RC 5

2015-07-22 io.js v3.0.0 RC 4

doc: Add notes for using @@toStringTag