release 0.2.2 prep

[dekellum]

Please note change log update suggests this will be released today. Also please tag it.

Changes as per master 722df55 vs 0.2.1:

• Fix (potential double) panic of (HeaderMap) OccupiedEntry::remove_entry and remove_entry_mult when multiple values are present. (#446, #449 @dekellum)
• Safety audits of (priv) ByteStr and refactor of Authority (#408, #414 @sbosnick)
• Fix HeaderName to error instead of panic when input is too long (#432, #433 @acfoltzer)
• Allow StatusCode to encode values 100-999 without error. Use of the unclassified range 600-999 remains discouraged. (#144, #438, #443 @quininer @dekellum)
• Add String and &String fallible conversions to PathAndQuery (#450 @mkindahl)
• Fix Authority (and Uri) to error instead of panic on unbalanced brackets (#435, #445 @aeryz)

[dekellum]

Thanks!