Redis Cache: Save a roundtrip on delete

Don't have a separate "exists" roundtrip when deleting a key, simply
read from the return value from the delete operation itself.
Merge pull request #603 from klauspost/develop

Redis Cache: Save a roundtrip on delete
Allow errors from redis delete calls to be returned

Extension to #603
Added MakeMultipartRequest which issues multipart requests for the supplied HTTP method

formatted with go fmt

updated the case of content-type to Content-Type in MakeMultipartRequest()
Merge pull request #610 from thereallisa/master

Added MakeMultipartRequest() to the TestSuite
Fix `go vet` problems (#599)
Fix failed test
Reference correct source of goauth2 for CI runs
Merge pull request #612 from revel/fix-ci-package-error

Fix CI package error
Merge pull request #611 from landr0id/fix-vet-problems

Fix "go vet" problems
Fix typo (guarunteed -> guaranteed)
separate TemplateLoader.templateSet and make it more common
introduce TemplateEnginer interface, easying 3d-party template parser support.
rename TemplateFuncs to TemplateHelpers
make template enginer configurable
refactor NewTemplateLoader(paths []string) to NewTemplateLoader(name string, paths []string)
fix typo
use config template engine if exists
new TemplateEnginer.SetOptions(*config.Config) api for engine configuration
support config delim for GoTemplateEngine