title: Cannot resolve column name among field names
body: <p>I have created a dataframe as below:</p>
  
  <pre class="lang-scala prettyprint-override"><code>val bankDF = sqlContext.read.format("com.databricks.spark.csv").option("header","true").option("inferSchema","true").option("delimiter",";").load("/user/pvviswanathan_yahoo_com/Bank_Dataset.csv");
  
  bankDF: org.apache.spark.sql.DataFrame = ["age";"job";"marital";"education";"default";"balance";"housing";"loan";"contact";"day";"month";"duration";"
  campaign";"pdays";"previous";"poutcome";"y": string]
  </code></pre>
  
  <p>After that when I tried the below, it is throwing error - Cannot resolve column name "age" among field names</p>
  
  <pre class="lang-scala prettyprint-override"><code>bankDF.groupBy("age").count().show;
  
  org.apache.spark.sql.AnalysisException: Cannot resolve column name "age" among ("age";"job";"marital";"education";"default";"balance";"housing";"loan
  ";"contact";"day";"month";"duration";"campaign";"pdays";"previous";"poutcome";"y");
  </code></pre>