Log script change/add and removal at INFO level

[dakrone]

Now that dynamic scripting is disabled, it's extremely helpful to know if/when a script is added or removed via the ScriptChangesListener, previously these were only TRACE level messages, they now look like:

[2014-05-09 12:01:25,393][INFO ][script                   ] [Plunderer] compiling script file [/Users/hinmanm/src/elasticsearch/config/scripts/calculate-score.mvel]
[2014-05-09 12:02:25,397][INFO ][script                   ] [Plunderer] compiling script file [/Users/hinmanm/src/elasticsearch/config/scripts/test.mvel]
[2014-05-09 12:03:25,399][INFO ][script                   ] [Plunderer] removing script file [/Users/hinmanm/src/elasticsearch/config/scripts/test.mvel]

To give an indication as to when the script changes have noticed and the scripts added/reloaded/removed.

[pickypg]

LGTM. Certainly an improvement to have it pass in the argument as opposed to always concatenating it anyway.

[jpountz]

It looks good to me as well!