Escape Unicode characters in test data.

This enables reproducible builds with non-Unicode locales.

briar-core/src/main/java/org/briarproject/briar/test/TestData.java

@@ -19,7 +19,7 @@ public interface TestData {
 			"Ibrahim ibn Sinan",
 			"Muhammad Al-Karaji",
 			"Yang Hui",
-			"René Descartes",
+			"Ren\u00e9 Descartes",
 			"Pierre de Fermat",
 			"Blaise Pascal",
 			"Jacob Bernoulli",
@@ -33,13 +33,13 @@ public interface TestData {
 			"George Boole",
 			"John Venn",
 			"Gottlob Frege",
-			"Henri Poincaré",
+			"Henri Poincar\u00e9",
 			"David Hilbert",
 			"Bertrand Russell",
 			"John von Neumann",
-			"Kurt Gödel",
+			"Kurt G\u00f6del",
 			"Alan Turing",
-			"Benoît Mandelbrot",
+			"Beno\u00eet Mandelbrot",
 			"John Nash",
 			getRandomString(MAX_AUTHOR_NAME_LENGTH),
 			getRandomString(MAX_AUTHOR_NAME_LENGTH),