Update Lo-Dash, QUnit, underscore.js and UNderscore.string.js for running tests with fresh versions.
Add new functions and tests of Undercore.js between 1.4.4 and 1.5.2 versions
Add new functions and tests of Undercore.string.js between 2.3.1 and 2.3.3 versions
Update README.md

[ci skip]
Version bump to 0.6.0