print non-fatal errors to stdout instead of stderr

e.g. docopt treat version as non-fatal error

Fixes #1033
fix fatal condition
add test: cargo --version
auto merge of #1051 : liigo/cargo/print-version-to-stdout, r=alexcrichton

e.g. docopt treat version (and help) as non-fatal error

Fixes #1033
Warn if none of documentation, homepage or repository are provided

It's really hard to find out any information about a project if it
doesn't have any of these.

As a bonus I added a shebang to .travis.install.deps.sh so the README
instructions actually work.

Closes #998
auto merge of #1053 : sfackler/cargo/master, r=alexcrichton

It's really hard to find out any information about a project if it
doesn't have any of these.

As a bonus I added a shebang to .travis.install.deps.sh so the README
instructions actually work.

Closes #998
Fix mac nightly builds

Older versions of curl apparently don't peel off the query parameters when
looking up filenames, so make two copies of the search results file in hope that
curl will find one of them!
auto merge of #1057 : alexcrichton/cargo/fix-nightly, r=brson

Older versions of curl apparently don't peel off the query parameters when
looking up filenames, so make two copies of the search results file in hope that
curl will find one of them!