correction to error message in SessionFactory

[gbirchmeier]

When the DD parser fails, the error message has 2 problems:

• it doesn't convert the DD path from byte-array to string, thus the user sees a bunch of ints
• missing single quote at the end

See the UT that I added. Without the code fix, the test fails with this:

=== RUN   TestSessionFactorySuite/TestBadDictionaryPath
    session_factory_test.go:753: 
        	Error Trace:	/Users/grantb/fork/qfgo/session_factory_test.go:753
        	Error:      	"problem parsing XML datadictionary path '[102 105 108 101 47 100 111 101 115 47 110 111 116 47 101 120 105 115 116 46 120 109 108]' for setting 'DataDictionary: problem opening file: file/does/not/exist.xml: open file/does/not/exist.xml: no such file or directory" does not contain "problem parsing XML datadictionary path 'file/does/not/exist.xml' for setting 'DataDictionary':"
        	Test:       	TestSessionFactorySuite/TestBadDictionaryPath
--- FAIL: TestSessionFactorySuite/TestBadDictionaryPath (0.00s)

After the code fix, the test passes. The corrected error content starts with:

"problem parsing XML datadictionary path 'file/does/not/exist.xml' for setting 'DataDictionary':"

(note the formerly-missing single-quote before the end colon)