PDB-1476 - Invalid SQL when calling a parameter as a non-admin user

This issue reproduced with another exception:
08:03:51,179 ERROR [DashboardRenderer] ad7ee7b8-59e7-11e4-8cfa-080027006067:DASHBOARD-ENGINE:: DashboardRenderer.ERROR_0021- Could not render dashboard
java.io.FileNotFoundException: Repository file /public/dasboard/11.xdash/11.xdash not readable or does not exist at org.pentaho.platform.repository2.unified.fileio.RepositoryFileInputStream.RepositoryFileInputStream.java:63)

Reason: incorrect saving dashboard - in resulting xdash file contains widgets with incorrect "xdash" parameter. It contains path with double file name.

I fixed it.

Additional information see in https://github.com/pentaho/pentaho-platform-plugin-dashboards/pull/171

@rfellows verify please