Merge pull request #4 from sfackler/master

Allow specification of additional objects to link in
Support for iOS compilation
Merge pull request #5 from vhbit/ios-support

Support for iOS compilation
Add some metadata and bump the version number
Improve error messages slightly around running commands
Bump to 0.1.0
Add Windows notes

not obvious, might be helpful
Tweak wording around gcc on windows
Support use of namespaced environment variables based on TARGET and HOST
Merge pull request #9 from jmesmon/namespace-env

Support use of namespaced environment variables based on "TARGET" and "HOST"
Fix case when 'HOST' is not set on OSX

Instead of using “gcc” it fails, so by using `Result` instead of
`Option` the error message can be returned instead of causing task
panic.

Fixes https://github.com/rust-lang/time/issues/28
Fix README link failed

add `cargo's build-script driver` link
Merge pull request #10 from bvssvni/osx

Fix case when 'HOST' is not set on OSX
Merge pull request #11 from SerhoLiu/fix-readme-link

Fix README link failed
Don't fail when all envs are unset. Also log envs checked.
Merge pull request #12 from DiamondLovesYou/cross-compile-fix

Don't fail when all envs are unset. Also log envs checked.
Remove uneeded feature