Rename Date to PosixDate

[slayful]

#1902

• Date -> PosixDate.
• If any of the creation arguments is negative set them to zero.
• Tests for PosixDate.

[SeanTAllen]

Thanks @slayful.

In the future, can you add more informative commit messages, perhaps stealing some reasoning from the issue and include a "Closes #XXXX"?

Both those will help us greatly.

Once this passes CI, I'm going to squash your commit, add a good commit message explaining the change and then close the corresponding issue.

[SeanTAllen]

We need to update the changelog-tool before this can be merged and then .travis_script.sh will need to be updated as part of this PR to use the correct version of the changelog-tool.

[SeanTAllen]

I'm leaving this for now. @Theodus lets discuss how to handle this at the next sync. This will come up from time to time and I think its a good chance to figure out how we will deal with. Sorry this will delay your PR @slayful.

[slayful]

No problem, thanks for the update. :)

[Theodus]

@SeanTAllen is going to setup a linux bintray release of the changelog-tool so that we don't require building it from source in the ponyc CI. Once that is done and the travis config is updated this will require a rebase.

[SeanTAllen]

@slayful can you rebase against master and force push to this branch? that should clear up the failure.

[slayful]

@SeanTAllen done - hopefully that will resolve any issues :)

[SeanTAllen]

thanks @slayful