Monitoring using new views

In pull request #4158 I created three new views that provide the size of the files (and the file count) for transfers and publication. Here I updated the monitoring to use these new views when doing the plots in the index.html, publish.html and dest-source-stat.html. 
IMPORTANT: the current patch requires patch #4158 to be applied aswell.
There is now a menu from where the user can choose the quantity used in the y axis for the plots. The options are: 1) the files counts (as it was before), and 2) the files size in MB. I also added a new button "Reload Plots" that onclick will read all the options in the form (start/end date/time and the y axis unit) and then calls drawchart(). There is now a function setOptions() that (as the name says) sets all the options (so far start/end date/time and y axis unit) before plotting. This function is called always before calling drawchart(). In this way the setting of the options and the plotting are now separate from each other. 
I also improved the way the date/time form is presented and used. For example, under a click on the "Default" button the date/time form is reset to blank, the flag defaultDateTime is set to true, and then the functions setOptions() and drawchart() are called. The setOptions() function reads the date/time form and the y axis form; if at least one date/time field is empty (i.e. not set) in the form, then the function sets the defaultDateTime flag to true and resets the date/time to blank; if all the fields are filled then the plots are done using the specified start/end date/time. To me this looks much more cleaner to the user.