Change API: Container => File.

Rename ZipContainer::Container to ZipContainer::File. This makes more sense as
we are dealing with actual file serializations of containers. It also matches
the rubyzip API more closely which will become even more obvious when other
rubyzip API entry points (OutputStream, InputStream) are implemented.
Refactor exceptions so we can shadow rubyzip exceptions.

This so we can stop rubyzip leaking out.
Use the shadowed ZipError in the tests.
Use the shadowed ZipError in the example scripts.
Update the exceptions to use Zip::Error.

Zip::ZipError is the old name for that class.
Merge branch 'rh/file' into next

* rh/file:
  Change API: Container => File.

Conflicts:
	test/tc_create.rb
	test/tc_read.rb
Fix missed Container => File rename.
Refactor managed file and directory initializers.

A more flexible, extendable interface.
Fix two more missed Container => File renames.

Gah!
Add the new Util module with a helper method.
Toggle managed files as hidden in normal use.
Update find_entry to take hidden files into account.
Fix the managed files and directories lists.

Things were not recursing into directories properly.
Update the hidden file detection code.

Now takes into account deep directory trees.
Cache managed entry lists.
Split up the hidden entry/find_entry tests.
Update get_entry to take hidden files into account.
Merge branch 'master' into next

* master:
  Bump to version 2.0.0.
Mixin the Util module to the ManagedEntry class.

Util.entry_name is really useful for subclasses of ManagedEntry.
Update glob to take hidden files into account.