Add per podspec compiler flags support and Specification#requires_arc shortcut

By default use the same header dir for pod that are part of another pod. This can be changed by specifiying a custom `header_dir`. Closes #14.

Copy headers to the pod's header dir $(BUILT_PRODUCTS_DIR)/Pods/PodName by default, but allow for customization by overriding copy_header_mapping(s).

In progress work to close Issue 14, the directory structure is now preserved for headers being copied in, need to update specs to match

Add each project to the header search paths. This will allow for both styles of includes. Need to figure out about maintaing directory structure though

Fixes a small typo in search result text.

"whose" would be correct if pods were persons. I changed it such that it uses "with",
as in "Unable to find a pod with name matching ..."

Add headers to the PBXCopyFilesBuildPhase instead of the PBXHeadersBuildPhase to work around an Xcode bug. Closes #13.

Update README to point to the MacRuby installer pkg and a link to a wiki page with instructions for developing on CocoaPods.

We'll need this to support #8.

From:
https://github.com/gowalla/AFNetworking/tree/master/Example