Continuing unit tests and minor bug fixes

* Support unit tests on Yubikey NEO
* Test ykpiv_get_version
* Test ykpiv_import_private_key
* Test ykpiv_sign_data
* Test ykpiv_decipher_data
* Test ykpiv_change_pin
* Test ykpiv_change_puk
* Test ykpiv_get_pin_retries
* Test ykpiv_set_pin_retries
* Test ykpiv_verify
* Fix segfault when |tries| is NULL
* Fix segfault when import_private_key algorithm is wrong

.gitignore

@@ -43,12 +43,19 @@ lib/tests/parse_key
 lib/tests/parse_key.log
 lib/tests/parse_key.o
 lib/tests/parse_key.trs
+lib/tests/util
+lib/tests/util.log
+lib/tests/util.o
+lib/tests/util.trs
 lib/tests/test-suite.log
 lib/error.lo
 lib/error.o
 lib/libykpiv.la
 lib/version.lo
 lib/version.o
+lib/util.la
+lib/util.lo
+lib/util.o
 lib/ykpiv-version.h
 lib/ykpiv.lo
 lib/ykpiv.o
@@ -97,3 +104,9 @@ ykcs11/tests/ykcs11_tests.o
 ykcs11/tests/ykcs11_tests.trs
 ykcs11/tests/test-suite.log
 yubico-piv-tool.1.txt
+
+*.plist
+.libs
+GPATH
+GRTAGS
+GTAGS