Dynamic catalog: add includeBrokersRegexp

[gberche-orange]

Expected behavior

• As an osb-cmdb operator
• In order to have more fine grain control over included brokers
  • E.g. trouble managing service plan visibility on some legacy environment, see https://github.com/orange-cloudfoundry/paas-templates/issues/432
  • As a workaround for Dynamic catalog to honor service plan access #2
• I need to be able to specify a rexexp of service broker names to include

Observed behavior

Only a rexgexp of service brokers to exclude is available. This makes a lengthy regexp which is fragile and not robust to future addition of new brokers

Affected release

Reproduced on version 0.9