Cherry-picking change I476e5a00 from eclair-china

Add Hanzi to Pinyin converter and sort key for contacts

Sort key and Hanzi to Pinyin converter is used for Chinese
implementation of contacts search, indexing and sorting.
Hanzi to Pinyin converter should be implemented on top of ICU
transliterator in the future.

Change-Id: I620f67c85897ee4054eda2624e7bcc12a81740aa