additional logging for licenses

Author: goneall

src/main/java/org/spdx/library/ListedLicenses.java

@@ -126,7 +126,7 @@ private void initializeLicenseModelStore() {
         		try {
         			baseModelStore = new SpdxListedLicenseLocalStore();
         		} catch(InvalidSPDXAnalysisException ex) {
-        			logger.error("Error loading cached SPDX licenses");
+        			logger.error("Error loading cached SPDX licenses", ex);
         			throw new RuntimeException("Unexpected error loading SPDX Listed Licenses");
         		}
         	}

src/main/java/org/spdx/storage/listedlicense/SpdxListedLicenseModelStore.java

@@ -180,8 +180,10 @@ private void loadIds() throws InvalidSPDXAnalysisException {
                 ExceptionJsonTOC exceptionToc = gson.fromJson(tocJsonStr.toString(), ExceptionJsonTOC.class);
                 exceptionIds = exceptionToc.getExceptionIds();
             } catch (MalformedURLException e) {
+				logger.error("License TOC URL invalid", e);
 				throw new SpdxListedLicenseException("License TOC URL invalid", e) ;
 			} catch (IOException e) {
+				logger.error("I/O error reading license TOC", e);
 				throw new SpdxListedLicenseException("I/O error reading license TOC", e);
 			} finally {
             	if (reader != null) {