hybrid: makes colors consistent across the modes

[ikalnytskyi]

hybrid.vim theme for airline uses pretty strange palette for both visual
and insert modes. Despite looking strange, one may consider it as a
design decision, however, the replace mode uses the same palette for
statusline as the normal mode and hence looks consistent. Visual
comparison could is located here:

http://imgur.com/a/YoeMS

This patch makes things consistent and use the same colors for the
status line, and different colors for mode indicator.

[chrisbra]

thanks.