CB-5720 add resource-file to plugin.xml
CB-5720 add resource-file to plugin.xml for all platforms
reverted last change because ios does already support resource-file
CB-5720: emit warning if resource-file is not supported on platform
CB-5006 Fix searchpath not being passed to dependent plugins.
CB-5802 Updated version and RELEASENOTES.md for release 0.18.0
Bump node-xcode dependency version
Update node-xcode dependency to 0.6.6
CB-5299 Cache pbxproj to avoid re-parsing it for each plugin.

Parsing pbxproj is very slow (~250ms on my machine). It is done for each plugin
that needs to add frameworks to the ios project. This change is a quick and
dirty fix to allow caching the parsed pbxproj object so that it can be reused for
multiple plugins during prepare.

Timings on a test project for cordova prepare ios:
before: 1.623s
after:  0.981s
CB-5804: added repo & issues to plugman publish
CB-5891 Fix engine check when path has spaces.
updated release notes
Setting version to 0.19.0
Tweak release notes
CB-5962 Incremented plugin version to -dev branch.
Updated readme to reflect that Windows8 IS supported
wip implementing reading guid from 'framework' project
more work on adding project to solution
CB-5990 Delete unused findPlugins() function
CB-5017 accept proxy config for plugman

plugman does not honor proxy configuration. take the same apporach as
npm itself and use "request" module to handle proxy config.

this commit also introduces changes to dependencies:
 + request
 + tar
 - tar.gz