brooklyn.properties: configure file locations, and support local

- adds BrooklynProperties.Factory.Builder, where can set paths
  for various properties files (rather than all hard-coded)
- brooklyn script (i.e. Main class) accepts --localBrooklynProperties
  to specify a file that appends to and overrides values in global
  brooklyn.properties
- BrooklynNode takes "global" and "local" property files contents
Adds JcloudsLocationConfig.TAGS

- sets jclouds TemplateOptions.tags(...)
EntityDynamicType.buildConfigKeys: avoid fail if field inaccessible

- if a field is inaccessible, warn and continue rather than throwing
  exception (previous no config keys are reported)
- can happen if an entity declares private ConfigKey
adds/uses `ResourceUtils.mergeFilePaths(String…)`