Build: Add ignoreDirtyWorkTree property

Setting the value of this property to true will omit the `--dirty` flag
to `git describe` when generating the `git.commit.name`. This is helpful
when comparing the build output to a previous build after making an
uncommited change.

Signed-off-by: Tony Germano <[email protected]>

Author: tonygermano

server/mirth-build.xml

@@ -1,4 +1,4 @@
-<project name="mirth-connect" basedir="." default="build">
+<project name="mirth-connect" basedir="." default="build" xmlns:unless="ant:unless">
 	<macrodef name="exec-with-default">
 		<attribute name="executable" />
 		<attribute name="property" />
@@ -58,7 +58,7 @@
 				<arg value="v[0-9]*" />
 				<arg value="--tags" />
 				<arg value="--long" />
-				<arg value="--dirty" />
+				<arg value="--dirty" unless:true="${ignoreDirtyWorkTree}"/>
 			</args>
 		</exec-with-default>
 		<echo>Using git.commit.name of [${git.commit.name}]</echo>