[R.I.P.] Remove python2legacy and hospython2legacy

[opacam]

Because:

• pygame has been removed (one of the purposes of this recipe was to make it work that bootstrap, alongside to be able to target api levels below 21)
• the end of life of Python 2 it's near (2020)
• we still have the python2 recipe (version 2.7.15)

Caveats:

• We loose the ability to target api levels below 21 (Android 5.0 - Lollipop)

See also:

• https://developer.android.com/about/dashboards
• open discussion about removing things at Suggestion: getting rid of some things #1782

If the code you care about is still on Python 2...the clock is ticking...https://pythonclock.org/

As a side note: I don't think that we can get a green tick mark with this pr in travis...this pr has all the numbers to fail with our CI test rebuild_updated_recipes...similar than the recently merged pr about the pygame removal

[inclement]

I have no objections to this. I'll merge as soon as I have time to review it, or if others are looking at it then go ahead as far as I'm concerned :)

Thanks @opacam

[inclement]

Looks solid, thanks again @opacam :)

[AndreMiras]

Nice to see it goes 👋
Funnily my tox tests/test_graph.py were failing until I deleted the empty directories left over after rebasing to master.
The error was:

AttributeError: module 'pythonforandroid.bootstraps.pygame' has no attribute 'bootstrap'

I had to delete the following empty directories:

• pythonforandroid/recipes/pygame*
• pythonforandroid/recipes/*python2legacy