Removes unused lru-cache dependency.
fixes URLs to reflect current repository ones
Changes assert.imageEqualsFile to accept per mil tolerance instead of per cent. Creates constant value for tolerance for multilayer and server_gettile suites.
Adds reference to README about issues with ImageMagick and tests. Also replaces tab indentation with spaces.
Fixes typo in repository URL
Adds Function type hinting to assert.response as it accepts also function as msg param.
Merge pull request #181 from rochoa/master

Minimal changes to get tests running in Mac OS X plus other cleanups