Unify processor interface. Check boundaries while processing. Fixes #205

This commit unifies the interface of all `SectionProcessorBase` `process...` methods.
Previously, it was expected that `processSignature()`, `processDescription()` and `processContent()`
always processes exactly one node (or none). However with the Blueprint `SectionProcessor` processing (arguably not correctly)
multiple nodes it is clear that is essential to expect any `process...` methods to process an arbitrary number of nodes. For this
the interface of aforementioned nodes needed to be extended to allow checking the boundary of the node iterator.
Merge pull request #206 from apiaryio/zdne/uniform-processor-interface

Unify processor interface. Check boundaries while processing. Fixes #205
Add deprecated headers back to integration tests
Cleaned up indentation
Use actionHTTPMethodAndName in action's parseSignature
Merge pull request #207 from apiaryio/pksunkara/review-fixes

Review fixes
Update Xcode project (remove removed file)
Merge pull request #208 from apiaryio/zdne/xcode-update

Update Xcode project (remove removed file)
Merge pull request #203 from apiaryio/shared/refactor-integration

New parser architecture.
Prepare for the v0.14.0 release
Merge pull request #210 from apiaryio/zdne/prepare-v0.14-release

Prepare for the v0.14.0 release