Do not set changeps1 to false as that affects deactivation of PS1 on bash

Closes #16

See merge request !30

[bootstrap] Do not set changeps1 to false as that affects deactivation of PS1 in hybrid environments (closes #16); Remove unused channels from default environment

Do not overwrite conda-build root dir if already configured

See merge request !25

The condarc file can contain the root-dir entry which state where
conda-build should run and store its artifacts. Don't set croot
if that setting is found.

Add notes about linux CI setup

See merge request !29

Nightlies

See merge request !28

Add missing parameter to create script (closes #15)

See merge request !27

New functionality for enabling/disabling and inspecting runners

See merge request !26