test: add test samples

Adds test samples that can be used for unit tests or to verify
implementations via:
```bash
for sample in $(ls src/test/resources/samples/*.txt)
do
  echo "Validating $sample"
  rm -f measurements.txt
  ln -s $sample measurements.txt

  diff <(./calculate_average.sh) ${sample%.txt}.out
done
rm measurements.txt
```

For #61

.gitignore

@@ -41,4 +41,4 @@ nb-configuration.xml
 #JReleaser
 out/
 
-measurements*.txt
+/measurements*.txt

src/test/resources/samples/measurements-1.out

@@ -0,0 +1 @@
+{Kunming=19.8/19.8/19.8}

src/test/resources/samples/measurements-1.txt

@@ -0,0 +1 @@
+Kunming;19.8

src/test/resources/samples/measurements-10.out

@@ -0,0 +1 @@
+{Adelaide=15.0/15.0/15.0, Cabo San Lucas=14.9/14.9/14.9, Dodoma=22.2/22.2/22.2, Halifax=12.9/12.9/12.9, Karachi=15.4/15.4/15.4, Pittsburgh=9.7/9.7/9.7, Ségou=25.7/25.7/25.7, Tauranga=38.2/38.2/38.2, Xi'an=24.2/24.2/24.2, Zagreb=12.2/12.2/12.2}

src/test/resources/samples/measurements-10.txt

@@ -0,0 +1,10 @@
+Halifax;12.9
+Zagreb;12.2
+Cabo San Lucas;14.9
+Adelaide;15.0
+Ségou;25.7
+Pittsburgh;9.7
+Karachi;15.4
+Xi'an;24.2
+Dodoma;22.2
+Tauranga;38.2

src/test/resources/samples/measurements-2.out

@@ -0,0 +1 @@
+{Bosaso=19.2/19.2/19.2, Petropavlovsk-Kamchatsky=9.5/9.5/9.5}

src/test/resources/samples/measurements-2.txt

@@ -0,0 +1,2 @@
+Bosaso;19.2
+Petropavlovsk-Kamchatsky;9.5