Fixing bug with empty sqlfilter

Occurs when there are no create/replace statements in the sql file being executed (oracle_lib.find_entities returns an empty dict).  The second parameter being sent to RunSQL.sql is empty and the USER_ERRORS select statement fails with an error, even though the sql file was executed successfully (which can be confusing to the user).  This fix simple sends an empty string as the second parameter in the case when no entities are returned by oracle_lib.
Support file paths with spaces

Adds support for the directory the script is saved in to contain spaces.  SQLPLUS has issues with spaces in filenames so we need to set the working directory to the one the script is in and then send SQLPLUS the script without the path.
Merge pull request #10 from jbjornson/patch-1

oracle_exec.py - bug with empty sqlfilter