Added 'no streams' UI text
Disabled button image added
gui refactoring: renamed controller package to cont
gui: disabled acquisition button bitmap file
gui refactor: renamed config package to conf
gui: refactoring
gui: Enable/disable the acquisition button according to visible streams in the current view
gui refactoring: Moved code from stream component to stream controller
gui: bug fix
gui: don't fail estimating time of camera's without readoutRate

Already tried to handle this with catching AttributeError exceptions, but
python complains about TypeError because it's in a division. So instead,
explicitely check readoutRate is a VA.

Also fix the error message.