Allow OPTIONS and PATCH requests in the standalone server.

Overrides the valid_http_method() method inherited from HTTP::Server::Simple
to allow all request types that the DSL supports.
Use a locally scoped variable to iterate through the execution of hooks

Previously $_ was used to iterate through the list of hook coderefs to
execute, however the aliasing involved allowed the hooks code to be
replaced if $_ was assigned within the hook code.

Resolves #540.
Merge pull request #535 from PerlDancer/pr/server_standalone_options_patch

Allow OPTIONS and PATCH requests in the standalone server.
Merge pull request #541 from PerlDancer/pr/no_default_scalar_in_execute_hook

Use a locally scoped variable to iterate through the execution of hooks
Update headers:

The file handler did not update the following headers:
- Content-Type
- Content-Length
- Last-Modified

This closes GH#550.
reflect change
Merge branch 'feature/update-response-headers'
Reflect changes for recent merges by @racke

Adds baynes to list of contributors.
Remove all test that use Dancer2::Test (except route PODs):

Finally.

Dancer2::Test is 864 lines of code, including documentation. It tries to fake
whatever is necessary to run a request against the Dancer2 code.

It is long, exhaustive, and hairy. It has subtle edge cases that required work
on both D1 and D2. It has been the bane of much testing code in Dancer. It also
has at least one bug (GH #544).

More than all of these, it simply isn't required. At least not the way it works
now. Plack::Test covers everything it does, except for checking POD coverage of
routes - which could be kept.

For now I've changed all the code that uses it to use Plack::Test instead. The
code is clearer and more maintainable.

Dancer2::Test will move to a relaxed deprecation cycle. We will add
documentation that shows a more preferred approach, including how to rewrite
existing tests.

An additional process requires having a simple method for fetching the PSGI app,
that will also call the "finish" methods on each Dancer application - tasks
that are more verbose without Dancer2::Test and expose more of the backend than
should be exposed (because it might actually change).
Added --directory option to dancer script
Merge pull request #553 from corecache/pr/542_dancer_app_directory

Enhancement #542 - added --directory option to dancer script
Merge pull request #552 from PerlDancer/feature/psgi-tests

Remove all test that use Dancer2::Test (except route PODs):
Reflect changes and update list of contributors.
BugFix #546 execute_hook return value
Added a saner test-description, since hooks may influence content, but not by return value
Reflect changes
Merge branch 'corecache-pr/546_execute_hook_return_value'
Fix: Additional HTTP methods for Ajax plugin #543
Merge pull request #561 from corecache/pr/543_allow_http_methods_ajax

Add additional HTTP methods for Ajax plugin (GH #543).
Minor cleanup of comments and POD in Ajax plugin.