Update getting_started.rst

add information about the environment variables.
Delete builds.rst

This chapter is no longer needed (duplicate content).
The content is alrady in http://gluon.readthedocs.org/en/latest/user/getting_started.html#getting-started .
Merge pull request #180 from pberndro/patch-1

Update getting_started.rst
Delete builds.rst

This chapter is no longer needed (duplicate content).
The content is alrady in http://gluon.readthedocs.org/en/latest/user/getting_started.html#getting-started .
Merge branch 'pberndro-patch-2'
Merge pull request #181 from pberndro/patch-2

Delete builds.rst
Update Gluon packages
Update upstream repos
docs: add documentation about addings new hardware support
Update LuCI
Update Gluon modules
Update OpenWrt and packages
docs: authorized-keys
Update Gluon packages