CPP: Move base code to i18n::phonenumbers namespace.

This is needed to avoid name clashes when the library is embedded into
Chromium.

BUG=http://crbug.com/236272
R=jia.shao.peng@gmail.com

Review URL: https://codereview.appspot.com/9029045

git-svn-id: http://libphonenumber.googlecode.com/svn/trunk/cpp/src/phonenumbers@569 ee073f10-1060-11df-b6a4-87a95322a99c
9 files changed