Implement Template#merge

This should fully encapsulate the logic of combining resources without
silently losing information.

Supports all merging combinations between
* Templates
* Hashes
* attributes defined as rich objects
* attributes defined as hashes.
Only merge with templates
Merge branch 'master' into rm/merge-template
Merge branch 'master' into rm/merge-template

Conflicts:
	lib/skywriter/template.rb
Fix #to_json issue
Add test of left side in merge
remove whitespace
Merge pull request #15 from otherinbox/rm/merge-template

Implement Template#merge