Improve use of exceptions overall

Add a few exception classes and use them. Fixes a few cases of throwing
strings instead of exceptions. Also resolves a slicing issue. Big commit!

Devices are not touched since they are changed dramatically in PNP.

Fixes #15 (though this doesn't include reconfiguration mode, we no longer
use issues to track long-term plans, but rather specific bugs).
trivial: remove an errant semicolon
Merge pull request #213 from scj7t4/exceptions

Improve use of exceptions overall
IBufferAdapter: print retrieved signal value to debug logger
IDevice: print retrieved signal value to debug logger
IDevice.cpp: use LF rather than CRLF line endings

Also, remove some trailing whitespace
simserv: fix rtdsadapter endian swap
simserv: drop rtdsadapter nan values before sending to pscad
Merge branch 'master' into PlugNPlay
Remove the PSCAD adapters from both DGI and PSCAD interface
IBufferAdapter: populate receive buffer with nan

This might break everything until Issue #122 is addressed.
CAdapterFactory: correct placement of debug statements
Merge branch 'PlugNPlay' of github.com:scj7t4/FREEDM into PlugNPlay
Fix filenames in headers of failure test cases
device manager thread safety
refuse subset of device states
simserv: forgot to drop pscad.xml
Merge branch 'PlugNPlay' into PNPTestCleanup