Recompile mruby scripts when configuration reloaded.

[syucream]

Current implementation compiles mruby scripts when ts_mruby plugin is initialized.
However, To improve operations of ATS, it should enable to recompile when configuration reloaded. (For example, when traffic_line -x is executed.)

• Check resources should be re-release/initialize when reloading
• Implement re-release/initialize logic
• Try $ traffic_ctl config reload

[syucream]

As soon as possible, it should be supported to enhance debugging... :)

[syucream]

Postpone to 0.2 because its a little heavy issue. Support reloading by traffic_line -x needs rethinking about more strict resource management.

[syucream]

After trafficserver-7.0.x, traffic_line is obsoleted. traffic_ctl config reload is alternative of traffic_line -x.