Optional lazy connect to SFDC by setting SF_LAZY_CONNECT. Fixes #71

It allows start of application even if SFDC is not currently accessible.
Fixed tests for lazy connect
Implemented recovery after repairing broken SFDC. #71
Security for tests: never send private data to nonexisting hosts
Locking for SF_LAZY_CONNECT.
Merge pull request #72 from hynekcer/lazy-connect

Lazy connect, fixes #71