unwrap values during fetch

fetching a value with #fetch a proc might be set to the specified key,
in order to unwrap all procs and only return the underlying value,
value.call is performed as long as it does not return any new proc
objects (e.g. it does not repond to :call any more).

fixes #859
Recapped an issue as a PR

fixed #694 Just listed out the other two ways to implement this as discussed in the issue.
Added support for subversion by extending pre-existing scm strategy, as noted in new documentation.
Add CodersClan to Contributing + other fixes

Fixed Stack Overflow and Mailing List links.
Add parameters to CodersClan links
Using `.rake` extension instead of `.cap`
In tests and default templates
Merge pull request #900 from kirs/rake-instead-of-cap

Using `.rake` extension instead of `.cap`.
Merge pull request #893 from Orchestrator81/master

Add CodersClan to Contributing + other fixes
Delete capistrano-public_cert.pem
Merge pull request #873 from signedbyte/patch-1

Recapped an issue as a PR.
Merge pull request #872 from Kriechi/fix_fetch_procs

Unwrap values during fetch.
Merge pull request #838 from chendrix/master

Added support for subversion by extending pre-existing scm strategy
Expose the release timestamp as :release_timestamp

Previously the only way to get this value was to extract it from
the end of :release_path.
Merge pull request #913 from arkadyan/expose_release_timestamp

Expose the release timestamp as a variable.