[cli] add --log option for `reframe start`...

[brillout]

...which would be passed down to createHapiServer.

(When createHapiServer is passed the argument log: true it prints build and page information.)
(createHapiServer is called in the cli.js file.)

[brillout]

@tdfranklin if you are up for it:)

[tdfranklin]

Ok, there ya go! See if that PR is what you're looking for and let me know if you want any changes.

[brillout]

Done