Add mgo files from core.
filetesting: create file with correct mode; test failures are annotated
Merge pull request #14 from rogpeppe/filetesting-improvements

filetesting: create file with correct mode; test failures are annotated
Update mgo tests, including package tests.
Changes to MgoSuite.
Receive the server cert and group data in a Certs struct.
Mgo suite comments. Remove MgoTestPackageSsl.
Merge pull request #16 from frankban/add-mgosuite

Add MgoSuite.