Update to Rust master: String conversion updates

As of rust-lang/rust/29bc9c632eda71c6b4a8b35db637971953b58d03 / rust-lang/rust#18976 `FromStr, from_str` have been moved to `std::str`.
Merge pull request #45 from msiemens/patch-1

Update to Rust master: String conversion updates
fixes for breaking change 'Switch to purely namespaces enums' commited to rust master at commit 3dcd2157403163789aaf21a9ab3c4d30a7c6494d
fix for deprecated find_copy
removed globbing in uses
Merge pull request #47 from CraZySacX/master

fixes for breaking change 'Switch to purely namespaces enums' commited t...
More fixes for enum namespaces.
Fixes warnings and errors

Mostly intruduced by recent changes regarding formatters. Closes #49
Merge pull request #50 from leonkunert/master

Fixes warnings and errors
crates.io support
Add an example for sub-commands.
fix parse_ty invocation (it accepts no arguments now)
Travis should also test docopt_macros
Merge pull request #52 from wackywendell/master

Travis should also test docopt_macros
Merge pull request #51 from jauhien/fix-parse_ty

fix parse_ty invocation (it accepts no arguments now)
Revert until parse_ty fixes makes it into nightly.

Revert "Merge pull request #51 from jauhien/fix-parse_ty"

This reverts commit e49741104573ef43b791ea3a2d790e6a0cae4217, reversing
changes made to 06fbbf1ee93dbf9983e2e4b8c9121b0ae0ae24a0.
removed :d format specifier
Gut the Makefile.

Didn't you hear? Cargo is the only game in town.
Say something about the convenient `exit` method in the docs.
Don't export the Value and Error variants explicitly.

The variants remain public (and there's no reason I see to change
that), but they are no longer exported as unnamespaced things mostly
because it's rare that you'll actually use them.

So imports like this:

  use docopt::{Docopt, Value, Switch, Counted}

should be changed to:

  use docopt::Docopt;
  use docopt::Value::{mod, Switch, Counted};

[breaking-change]