address reviews

...briarproject/bramble/api/contact/ContactExchangeTask.java

...ava/org/briarproject/bramble/api/contact/ContactInfo.java

.../org/briarproject/bramble/api/contact/ContactManager.java

...ava/org/briarproject/bramble/api/contact/ContactType.java

...ava/org/briarproject/bramble/client/ClientHelperImpl.java

...briarproject/bramble/contact/ContactExchangeTaskImpl.java

.../org/briarproject/bramble/contact/ContactManagerImpl.java

...va/org/briarproject/bramble/db/DatabaseComponentImpl.java

...c/main/java/org/briarproject/bramble/db/JdbcDatabase.java

.../briarproject/bramble/contact/ContactManagerImplTest.java

...st/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

...ain/java/org/briarproject/briar/blog/BlogManagerImpl.java

...arproject/briar/introduction/IntroductionManagerImpl.java

...r/privategroup/invitation/GroupInvitationManagerImpl.java

...rg/briarproject/briar/sharing/BlogSharingManagerImpl.java

...va/org/briarproject/briar/sharing/SharingManagerImpl.java