Fixes #22

Note that this only adds the new class library, it does not yet adjust
the existing service code to use it!

Refers to #21

An email will be sent only if the time since the last one exceeds the
new configuration option "GraceNotificationDelta", defaulting to 12
hours.

Fixes #1

Make GraceLocationSummary() return an empty string instead, if no
expired folders exist in the grace location.

Refers to #1

Plus also check if the repository's commit state is dirty and report
accordingly.

This is done using a git-hook script generating a text file which is
used as a resource by VS. The pre-build script in VS makes sure the file
is actually existing (using a default string) since otherwise the build
would fail.

Refers to #1

Refers to #1

Refers to #1

Refers to #1

Refers to #1

This is NOT YET reflected in the configuration example XML!

Plus make sure to not attempting to send the mail message if the
account name can't be resolved to an email address.

Catch exceptions in case setting the ACLs fails, make the operation
optional by adding the parameter resetAcls (defaulting to false).

Refers to #16

Using an optional element in the configuration XML, defaulting to "true"
via the configuration class constructor.

Refers to #16

Refers to #13