Restore the default starter if none is set

This commit fixes a regression introduced by the library refactoring.

Previously, if no dependency was selected, the default
'spring-boot-starter' was added to provide the necessary base
dependencies.

This commit adds a addDefaultDependency on ProjectRequest that
adds that dependency. It can be overridden if the default needs to be
different.

Fixes gh-34
Secure actuator endpoints
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Disable security
More detail in README
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