Placeholder view fix

Matched the location and colour of the placeholder with the one in JVFloatLabeledTextField.
Matched the frame of the placeholder UILabel with the frame of the JVFloatLabeledTextView so the line breaks automatically when expected
Adapted the example view controller to match the new JVFloatLabeledTextView behaviour where there is no need to know the textContainer.lineFragmentPadding

This is how it looks before these changes
![before](https://cloud.githubusercontent.com/assets/2027580/3081323/c487df74-e4bd-11e3-8a22-c7ce399715b7.png)

This is how it should look like, I have replaced the Description field to a textfield to show my point.
![textfield](https://cloud.githubusercontent.com/assets/2027580/3081334/d72c88e6-e4bd-11e3-9ed4-b13a364545e0.png)

This is how it looks with the changes made
![after](https://cloud.githubusercontent.com/assets/2027580/3081335/daeedb0a-e4bd-11e3-9540-3ffd6cafe5dd.png)