add last_write_time to metadata

[rustysec]

i added a feature which brings in chrono and the timezoneapi and minwinbase from winapi to provide a little abstraction of the FILETIME object that windows provides. with the feature on it extends RegKeyMetadata structure to provide the last_write_time field.

i also noticed when i opened the pr that rustfmt got hold of lib.rs and did some reformatting... i can definitely back out of that if you want.

[gentoo90]

I rustfmted everything. Can you rebase, so I could see which changes are yours?

[gentoo90]

Ok, so this pull-request was superseded by this which allows to get last_write_time without chrono and puts a conversion function under chrono feature.
Published to crates.io

Changelog

0.6.1

• Add last_write_time field to RegKeyMetadata (returned by RegKey::query_info()) (#25).
• Add get_last_write_time_system() and get_last_write_time_chrono() (under chrono feature) methods to RegKeyMetadata.