This catches responses that return <values> without associated <value>.

Example Below: 
  
  url = "http://waterservices.usgs.gov/nwis/iv/?format=waterml,1.1&huc=02&startDT=2014-10-11T00:00:00.000&endDT=2014-10-11T00:30:00.000&parameterCd=00060,00065"
  data <- getWaterML1Data(url)

WaterML Response (chunk)
  <ns1:timeSeries xmlns:ns1="http://www.cuahsi.org/waterML/1.1/" name="USGS:01350080:00065:00011">
  <ns1:sourceInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ns1:SiteInfoType">
  <ns1:siteName>MANOR KILL AT WEST CONESVILLE NEAR GILBOA NY</ns1:siteName>
  <ns1:siteCode network="NWIS" agencyCode="USGS">01350080</ns1:siteCode>
  <ns1:timeZoneInfo siteUsesDaylightSavingsTime="false">
  <ns1:defaultTimeZone zoneOffset="-05:00" zoneAbbreviation="EST"/>
  <ns1:daylightSavingsTimeZone zoneOffset="-04:00" zoneAbbreviation="EDT"/>
  </ns1:timeZoneInfo>
  <ns1:geoLocation>
  <ns1:geogLocation xsi:type="ns1:LatLonPointType" srs="EPSG:4326">
  <ns1:latitude>42.37694444</ns1:latitude>
  <ns1:longitude>-74.4130556</ns1:longitude>
  </ns1:geogLocation>
  </ns1:geoLocation>
  <ns1:siteProperty name="siteTypeCd">ST</ns1:siteProperty>
  <ns1:siteProperty name="hucCd">02020005</ns1:siteProperty>
  <ns1:siteProperty name="stateCd">36</ns1:siteProperty>
  <ns1:siteProperty name="countyCd">36095</ns1:siteProperty>
  </ns1:sourceInfo>
  <ns1:variable ns1:oid="45807202">
  <ns1:variableCode network="NWIS" vocabulary="NWIS:UnitValues" default="true" variableID="45807202">00065</ns1:variableCode>
  <ns1:variableName>Gage height, ft</ns1:variableName>
  <ns1:variableDescription>Gage height, feet</ns1:variableDescription>
  <ns1:valueType>Derived Value</ns1:valueType>
  <ns1:unit>
  <ns1:unitCode>ft</ns1:unitCode>
  </ns1:unit>
  <ns1:options>
  <ns1:option name="Statistic" optionCode="00011"/>
  </ns1:options>
  <ns1:noDataValue>-999999.0</ns1:noDataValue>
  </ns1:variable>
  <ns1:values>
  <ns1:method methodID="1">
  <ns1:methodDescription>[backup from well]</ns1:methodDescription>
  </ns1:method>
  </ns1:values>
  <ns1:values>
  <ns1:value qualifiers="P" dateTime="2014-10-11T00:00:00.000-05:00">0.85</ns1:value>
  <ns1:value qualifiers="P" dateTime="2014-10-11T00:15:00.000-05:00">0.85</ns1:value>
  <ns1:value qualifiers="P" dateTime="2014-10-11T00:30:00.000-05:00">0.85</ns1:value>
  <ns1:qualifier qualifierID="0" ns1:network="NWIS" ns1:vocabulary="uv_rmk_cd">
  <ns1:qualifierCode>P</ns1:qualifierCode>
  <ns1:qualifierDescription>Provisional data subject to revision.</ns1:qualifierDescription>
  </ns1:qualifier>
  <ns1:method methodID="12">
  <ns1:methodDescription/>
  </ns1:method>
  </ns1:values>
  </ns1:timeSeries>

Fixed sample user file function.

Fixed User sample function.

Fixed unit data examples.

Hard coding dates for unit value data. Otherwise, might ask for data from the future if outside the appropriate timezone.

Update README.md

Troubleshooting merge ref issues.

Update README.md

Readme cleanup.

Merge branch 'master' of github.com:USGS-R/dataRetrieval

Conflicts:
	README.md

Updating appveyor tolken.

Adding unix tests.

Added testthat.