feat/keep namespace filter

[mosheavni]

Save namespace filter to the kubectl.json file
also more elegant approach to saving a state to a file. we can reuse in the future.

Edit:
well.. sometimes it works, and sometimes it doesn't,
when it works it flashes between namespaced -> all -> namespaced
when it doesn't, it flashes namespaced -> all

which could cause epilepsy:

[mosheavni]

Fixed! NS filter is working :)

[mosheavni]

Made 2 fixes from my phone
First time committing from mobile.
ahh... the technology nowadays...

[Ramilito]

Did a small refactor if you wanted to look at what I ment!