Compare regexp as string.

Fix #1633.
Merge pull request #1636 from braddunbar/regexp-isequal

Compare regexp as string.
_.some via _.every
check predicate in a separate line
Merge pull request #1637 from mehdishojaei/some_via_every

_.some via _.every
Revert "Merge pull request #1637 from mehdishojaei/some_via_every"

This reverts commit 7feead9b2273daa82cb06f8c9580e94fe9fc58b1, reversing
changes made to a7ee4f95396f68cd4abefff841763d744f5f6251.
Abstract iterator binding to createIterator

Long coming optimization discussed in 1525, 1561 and elsewhere.
Follows lodash's lead.
Closes #1561; add lookupIterators as appropriate

See included tests and lodash docs for some examples

LookupIterators maps string properties (see #1557) and objects to
_.matches.

As a result several of the helper functions such as _.where, _.pluck,
_.findWhere are handled by their parent implementations.
Edge case compat for findWhere, where, pluck

As discussed in PR with jdalton and @bradunbar
Tweak tests.
Merge bradunbar's test tweaks+min/max test
Merge pull request #1582 from megawac/Iterators2

Abstract iterator binding to createIterator and callbacks to createCallback
remove unnecessary uses of `new` with native constructors

ref https://github.com/jashkenas/underscore/pull/1616#issuecomment-43547113
fixes #1641: _.min iterator should accept context
update npm during travis CI run to fix transitive caret (^) dependencies
fixes #1608: integrate eslint into testing process
Merge pull request #1616 from michaelficarra/GH-1608

fixes #1608: integrate eslint into testing process
remove unneeded predicate check
Merge pull request #1643 from mehdishojaei/remove-unneeded-predicate-check

remove unneeded predicate check
remove unneeded result check