Improve GL200 decoder (fix #830)
Support PT502 binary messages (fix #825)
Eliminated the need for hardcoded protocol strings in the src/org/traccar/protocol/*ProtocolDecoder.java files.
Made BaseProtocolDecoder members "final" as they should not change after construction.
Updated BaseProtocolDecoder constructor to take three parameters (DataManager, String, Properties);  Removed second constructor;
Merge pull request #918 from jon-stumpf/enhancement-eliminate-hardcoded-protocol-names

Eliminate hardcoded protocol names
Put back cache timeout (fix #933)