Revert "Allow multi-line config items in meta-section of local.conf"

This reverts commit 6ff21acf4c4d4ef08bbef419ba582cade4da8da7.

This commit has broken config options with colons in them.
The following is a sample configuration that no longer works:

[[post-config|/etc/neutron/plugins/ml2/ml2_conf.ini]]
[restproxy]
server_ssl=False
servers=10.211.1.9:80
server_ssl=False

With the above config and the code present that this reverts,
the 'servers' option will come out blank.

Change-Id: I328852d2d941605051a1bf5eaf0f7674191f8c48
Merge commit 'refs/changes/03/127603/1' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch