Assert RuntimeError when modifying frozen objects in Ruby 1.9 and beyond

Before trying to fix the invalid multibyte escape error in Ruby 2.0, I first
want to get the test_vcard.rb suite all green in Ruby 1.8.7, 1.9.2, 1.9.3 and
2.0.0.

This test failure resulted from the fact that as of Ruby 1.9, attempts to modify
frozen objects raise RuntimeErrors instead of TypeErrors.

    test_modify_name(TestVcard) [test/test_vcard.rb:693]:
    [TypeError] exception expected, not
    Class: <RuntimeError>
    Message: <"can't modify frozen Vpim::Vcard::Name">
    ---Backtrace---
    test/test_vcard.rb:694:in `block in test_modify_name'

The fix for this is simply to assert the correct type of error according to the
version of Ruby currently executing.
Add "encoding: utf8" comment in order to suppress encoding error message

This error message was being generated in Rubies 1.9.2, 1.9.3, and 2.0.0.

    test_ical_1(TestVcard): ArgumentError: invalid byte sequence in US-ASCII
    /Users/h2s/src/vpim/lib/vpim/rfc2425.rb:92:in `block in unfold'
    /Users/h2s/src/vpim/lib/vpim/rfc2425.rb:88:in `each_line'
    /Users/h2s/src/vpim/lib/vpim/rfc2425.rb:88:in `unfold'
    /Users/h2s/src/vpim/lib/vpim/rfc2425.rb:315:in `decode'
    test/test_vcard.rb:351:in `block in test_ical_1'

Adding a "#encoding: utf8" comment to the top of all the source code files using
the magic_encoding gem fixes the error. This now leaves only the invalid
multibyte encoding error to deal with.
1.9 compatibility, add cwd to default include path
Remove agent and repo tests from test_all

They aren't used, I don't want to install all the dependencies (like
libxml).