Fix digestion of templates with recursive dependencies.

Put a placeholder in the cache until the digest is computed.
Added a note about required restart

A restart is required whenever the template changes. 
As I don't think there is another solution,
it should be documented
Merge remote-tracking branch 'genezys/patch-1' into readme-development
Add more information about required server restart and how to avoid it
Merge pull request #24 from fgrehm/readme-development

Add more information about required server restart and how to avoid it
Merge pull request #10 from macournoyer/master

Fix digestion of templates with recursive dependencies
Support external dependencies specified via the options hash

This lets you control the created digest programmatically, for instance
when a different template was selected even though the format and
virtual path are the same.
use declarative api for describing view dependencies programmatically
rename view_dependency -> view_cache_dependency
Merge pull request #25 from jamis/master

Allow template dependencies to be specified programmatically
injected view dependencies are not templates

These injected dependencies should be included in the digest directly.

Also, we can get away with using the injected dependencies directly in the
digest cache key, rather than leaning on the cache_prefix. It's far
simpler.
Merge pull request #26 from jamis/master

Don't try to process injected view cache dependencies as templates
Raise a meaningful exception on rake tasks if TEMPLATE is not provided
Digestor explicit dependency should not contain trailing whitespace
Merge pull request #34 from balexand/match_not_whitespace

Digestor explicit dependency should not contain trailing whitespace (with tests)
Merge pull request #27 from fgrehm/exception-for-empty-TEMPLATE

Raise a meaningful exception on rake tasks if TEMPLATE is not provided
Format the regex with code delimiters

Makes the regex more readable.
Merge pull request #20 from dasch/patch-1

Format the regex with code delimiters
Extract the dependency tracking to DependencyTracker
Use handler-specific dependency trackers