perf ui browser: Make the colors configurable and change the defaults

Just use as a starting point the "[colors]" section of
tools/perf/Documentation/perfconfig.example.

Changed the colors to be the ones in the old perf tool if used in a green on
black xterm.

The next patches should allow using the colors configured for the xterm.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-3vqmyerkaqltqolmnlehonew@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>