[Pods] Generate unique .rcinfo for Pods directory

Generating unique .rcinfo for a project in Pods directory.

Context

Historically, for cocoapods plugin configuration .rcinfo contained always absolute paths so to make the cocoapods plugin simpler, we were able to reuse it for Pods project (import it with extra_configuration_file). However, #22 changed the way .rcinfo is generated and uses now relative paths (to make them VCS commitable). These relative paths are incorrect for the Pods project, as it is placed in a Pods subdirectory.

Fix

Example Pods/.rcinfo

Before

extra_configuration_file: "../.rcinfo"

After

cache_addresses:
- http://localhost:8080/cache/pods
primary_repo: # Some value
mode: consumer
xccc_file: "../.rc/xccc"
remote_commit_file: "../.rc/arc.rc"
prettify_meta_files: false

How to test?

Reproduce a scenario described here
Make sure SDWebImage prints in Xcode logs [RC] Cached build for SDWebImage target
Verify that the Pods/.rcinfo file contains all fields defined in .rcinfo and paths to files are aligned (contain extra ../)

Fixes $43

spotify / XCRemoteCache