Prevent drinks pouring a second time

[Danzibob]

Fixes #1
In our (slightly modified) version of this code, we found that disabling interrupts as soon as the button was pressed would prevent the bartender pouring 2 drinks consecutively without being prompted. Tested fairly thoroughly with both physical and remote (SSH) triggers.

[bjensen]

@Danzibob This PR (if its the same found in your DoubleDrinkFix branch), prevents the user from pouring three drinks in a row.

[atainter]

You've verified that this works? I had a weird issue where the program would crash when I retried to re-enable interrupts. I didn't get around to debugging it.

[syntos]

Hello,

I've modified my code:
def right_btn(self, ctx):
if not self.running:
self.stopInterrupts()
self.menuContext.select()
self.startInterrupts()

Now, drinks are not made twice and selecting drinks is working fine.
However, when I enter the configuration and select a pump with the select button the script crashes and I get this message returned:

Backend terminated or disconnected. Fatal Python error: Segmantation fault

Any idea what's happening here?
If I comment the stop and start interrupts I do not get these error but then my selected drink is made twice.

Thank you.