Add a custom error message argument for missing schema nodes

missing_msg lets the developer specify a custom message in place of the
default "Required" if the node is missing.
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prep for 1.0b1
Merge pull request #123 from veeti/missing_msg

Add a custom error message argument for missing schema nodes
fix resource warnings
Un-break wrapping of callable instances as 'colander.deferred'.

Fixes #141.
Change from de_DE to de.
all subclasses of SchemaNode need a ``typ``

also the docs are confusing with you do:
    from colander import SchemaNode
and then in the same code block you use ``colander.Range``, so I
formalized everything to use ``colander.*`` syntax.
Add message-id
Re-generate pot
Update Japanese Translations.
Re-generate Japanese mo
Add validator which succeeds if at least one of its subvalidators  succeeded.
Sign contributor agreement.
Merge pull request #154 from gjo/translation-ja-4

Translation ja 4
Merge pull request #142 from nightmarebadger/fix-translations

Move country specific locales to be default language locales.
Fix typo.
Merge pull request #158 from whiteroses/master

Fix typo.
Update fr localization
Merge pull request #163 from makinacorpus/fr_locale

Update fr locale