Only explode registry key if it can be tokenized

[Breakwell]

Description

Running "SELECT * FROM registry WHERE (path like ' ')" causes osquery to crash. This is due to the explodeRegistryKey function assuming that whatever string is passed into it is prepended with the registry hive.

Testing

Before:

C:\test>osqueryd.exe --allow_unsafe --S
Using a �[1mvirtual database�[0m. Need help, type '.help'
osquery> SELECT * FROM registry WHERE (path like ' ');

C:\test>

After:

C:\test>osqueryd.exe --allow_unsafe --S
Using a �[1mvirtual database�[0m. Need help, type '.help'
osquery> SELECT * FROM registry WHERE (path like ' ');
osquery>

[theopolis]

nitpick, do you mind updating this to use if (!toks.empty()) {

[Breakwell]

Done.