zebra: lsp_install() failed due to ZEBRA_FLAG_SELECTED check

zebra: lsp_install() failed due to ZEBRA_FLAG_SELECTED check

ZEBRA_FLAG_SELECTED hasn't been set yet by the time lsp_install is
called.  The call path is:
rib_process -> rib_process_add_fib -> zebra_mpls_lsp_install -> lsp_install

but ZEBRA_FLAG_SELECTED is set in rib_process after it calls
rib_process_add_fib.  I can't think of anything that it would hurt to
install the LSP regardless of whether ZEBRA_FLAG_SELECTED is set later.

I also cleaned up some UI (json and display the pretty label names
instead of their numeric values).

Signed-off-by: Daniel Walton <dwalton@cumulusnetworks.com>