Add tool-cache (#12)

* Add tool-cache

* Format

* Fix linux bug

* Update readme

* Package zip/unzip

* Reorganize

* Format

* unzip somehow got corrupted, fixing

* Resolve remaining todos

* Don't log everything

* Pass error codes

* linting

* Branding and nits

* Fix for mac

* clean up windows/nix logic

* Clean up tests

* Export HTTPError

* Add option for custom 7z tool

* Lint/format

* Dont wipe temp/tool directories

package.json

@@ -6,7 +6,6 @@
     "exec",
     "actions"
   ],
-  "author": "Bryan MacFarlane <bryanmac@microsoft.com>",
   "homepage": "https://github.com/actions/toolkit/tree/master/packages/exec",
   "license": "MIT",
   "main": "lib/exec.js",