Minor updates to 1.2.4

Metadata Wizard tweaks by Curtis Price (06112014)
-Built "clean" tbx file using ArcGIS 10.1 (saved as 10.0) to avoid
double tool display
-Various tweaks to USGS_MetadataTool.py to improve maintainability
-Modified validation code in tbx:
--create working folder in user TEMP (not C:\temp)
--modified validation to use type "Folder" not "Workspace" for metadata
working folder
--If folder is not available, standard ArcGIS error message is displayed
fixed curly quotes in README file