Some localization cleanup and doc to aid in customization:

* added locale/en/LC_MESSAGES/statusnet.po to make it easier to start customizing English texts
* added notes to locale/README about customizing and how to disable languages you haven't customized
* renamed PO templates from *.po to *.pot to match general conventions and reduce confusion for people trying to find which file they're supposed to edit

plugins/Sample/locale/Sample.pot

@@ -0,0 +1,56 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2010-03-01 14:58-0800\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=CHARSET\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=INTEGER; plural=EXPRESSION;\n"
+
+#: hello.php:115 SamplePlugin.php:266
+msgid "Hello"
+msgstr ""
+
+#: hello.php:117 hello.php:141
+#, php-format
+msgid "Hello, %s"
+msgstr ""
+
+#: hello.php:138
+msgid "Hello, stranger!"
+msgstr ""
+
+#: hello.php:143
+#, php-format
+msgid "I have greeted you %d time."
+msgid_plural "I have greeted you %d times."
+msgstr[0] ""
+msgstr[1] ""
+
+#: SamplePlugin.php:266
+msgid "A warm greeting"
+msgstr ""
+
+#: SamplePlugin.php:277
+msgid "A sample plugin to show basics of development for new hackers."
+msgstr ""
+
+#: User_greeting_count.php:163
+#, php-format
+msgid "Could not save new greeting count for %d"
+msgstr ""
+
+#: User_greeting_count.php:176
+#, php-format
+msgid "Could not increment greeting count for %d"
+msgstr ""