Add Logger.Reopen(), reopens fp for log rotation
Add ReopenOnSignalLoop(), calls Reopen() on signal

Update .gitignore
Add BrandscreenLogger

Add .gitignore changes
Propagage error if FileLogger did not open file
Always evaluate runtime fields in logging context

Do away with Logger.runtime and simply evaluate all runtime fields in
the logging context. This means that sync/async mode is always
dictated by the sync flag, and the user must be aware of using any
runtime fields and slowing down the logging context.

The runtime fields are evaluated and saved in the request type and
passed along to the record type.
Merge pull request #1 from cxong/master

Add log file reopening on signal and Brandscreen logger