You can now set Properties on the Attribute Resource and on an Attribute via an XML file.

Property Section for the Attribute Resource

This is an optional section describing a set of properties  that should be
added to the Attribute Resource.  The Property section is defined by a XML
**Properties** node which is composed of a set of children **Property** nodes as shown below:

```xml

  <Properties>
    <Property Name="pi" Type="Int"> 42 </Property>
    <Property Name="pd" Type="double"> 3.141 </Property>
    <Property Name="ps" Type="STRING">Test string</Property>
    <Property Name="pb" Type="bool"> YES </Property>
  </Properties>
```

You can also look at data/attribute/attribute_collection/propertiesExample.rst and smtk/attribute/testing/cxx/unitXmlReaderProperties.cxx for a sample XML file and test.

Also added toBoolean method to StringUtils:
The new method will convert a string to a boolean.  If the method was successful it will return true else it will return false.  All surround white-space is ignored and case is ignored.

Current valid  values for true are: t, true, yes, 1
Current valid  values for false are: f, false, no, 0