Statsd namespace is defined and used

Statsd code now lives in android::os::statsd namespace. Existing files
are largely modified to follow this convention.

Exception: parse_util, since it seems a bit different.

Test: code compiles and existing statsd_tests still pass
Change-Id: Idf92a071b9ed172d01eb3087a4fa3609d67a038c
diff --git a/cmds/statsd/src/LogReader.cpp b/cmds/statsd/src/LogReader.cpp
index 2a9e500..c9164f9 100644
--- a/cmds/statsd/src/LogReader.cpp
+++ b/cmds/statsd/src/LogReader.cpp
@@ -26,6 +26,10 @@
 using namespace android;
 using namespace std;
 
+namespace android {
+namespace os {
+namespace statsd {
+
 #define SNOOZE_INITIAL_MS 100
 #define SNOOZE_MAX_MS (10 * 60 * 1000) // Ten minutes
 
@@ -141,3 +145,6 @@
     return lineCount;
 }
 
+} // namespace statsd
+} // namespace os
+} // namespace android