Tests: preserving unit.log when run without restart.

Introducing "unit.log.Log" class for "unit.log" file management.
Moving "findall()" function into TestApplicationProto.
Using "os.kill()" to send signals.

test/unit/log.py

@@ -0,0 +1,23 @@
+UNIT_LOG = 'unit.log'
+
+
+class Log:
+    temp_dir = None
+    pos = {}
+
+    def open(name=UNIT_LOG, encoding=None):
+        f = open(Log.get_path(name), 'r', encoding=encoding, errors='ignore')
+        f.seek(Log.pos.get(name, 0))
+
+        return f
+
+    def set_pos(pos, name=UNIT_LOG):
+        Log.pos[name] = pos
+
+    def swap(name):
+        pos = Log.pos.get(UNIT_LOG, 0)
+        Log.pos[UNIT_LOG] = Log.pos.get(name, 0)
+        Log.pos[name] = pos
+
+    def get_path(name=UNIT_LOG):
+        return Log.temp_dir + '/' + name