title: pyqt - put color in a QTableView with existing data
body: <p>i need help to color my QTableView. @rainer helped me putting color when i  initialize a table, but now, i already have a table with data(but without color// my data is a csv opened in my table), and i want to create a button that when clicked it colors the tableview in some lines,  like when there is  a row with -2 (data), it will be color with blue color.. 
  -- I have a button and a table. This button load the csv data into my tableview. I want to have a new button that color the rows of this table. ( but color only rows that have -2 of data, for example)
  Some codes: </p>
  
  <pre><code>    self.fileName = (_fromUtf8('tweets.csv'))
      self.tableView = QTableView(self.tabSentimento)
      self.tableView.setGeometry(QRect(550,10,510,700))
      self.tableView.setObjectName(_fromUtf8("TabelaSentimento"))
      self.tableView.setModel(self.model)
      self.tableView.horizontalHeader().setStretchLastSection(True)
  
      self.pushButtonLoad = QPushButton(self.tabSentimento)
      self.pushButtonLoad.setGeometry(QRect(550,720,130,30))
      self.pushButtonLoad.setObjectName(_fromUtf8("buttonLoadCSV"))
      self.pushButtonLoad.setText(QApplication.translate("Form", "Process!", None, QApplication.UnicodeUTF8))
      self.pushButtonLoad.setStyleSheet('color:red;background-color:rgb(255, 255, 153);border:1px solid purple;')
      self.pushButtonLoad.clicked.connect(self.on_pushButtonLoad_clicked)
  
  
      def loadCsv(self, fileName):
          with open(fileName, "rb") as fileInput:
              for row in csv.reader(fileInput):    
                  items = [
                      QStandardItem(field)
                      for field in row
              ]
                  self.model.appendRow(items)
  
      def on_pushButtonLoad_clicked(self):
          print self.fileName
          self.loadCsv(self.fileName)
  </code></pre>