Warn junos users of unsupported features

[mpenning]

Github Issue #17 added junos-like support for searching brace-delimited configs; however, CiscoConfParse has limited support for junos config modifications. Some people are surprised when they modify junos configs with CiscoConfParse() and hit unexpected problems associated with adding or deleting trailing braces in the parsed configuration.

This is more of a usability problem than a technical problem. The unsupported junos features work, but they come with a caveat.
When someone uses CiscoConfParse to modify a junos config, they naturally expect to use the modified config in a router.
However, CiscoConfParse does not generate brace-delimited configs that can be pasted in devices like Juniper, Palo Alto, F5 or others.

This issue is opened to warn junos users of unsupported features.