fix(bump): fix error if neither bowerrc nor bower.json exist
fix(bump): fix error if neither bowerrc nor bower.json exist

If bowerrc  does not exist the build system / bump task assumes the default bower.json is used to configure bower. But if bower.json does not exist, the task will fail. This commit fixes it. The task configuration will contain bower.json only if it exists.

w11k/fabs