Fix comparison of integers with the bool type in test cases for the Trie class.

This commit fixes comparisons of different types when checking the
return values of `trie.findValue()` in the test cases in testFind().
In test cases in testErase(), the return values of that function are
correctly checked with the binary operation "!=".
Fixes automake error caused by the commit 9635494bf.

The commit 9635494bf renamed README with README.md, leading to
the situation automake is complaining that there is no `README`
in this project unless we specify the option `foreign` into Makefile.am.
Merge pull request #4 from tetsuok/fix-trie-main-test

Fix comparison of integers with the bool type in test cases for the Trie class
Merge pull request #5 from tetsuok/fix-autotools-readme-not-found-error

Fixes automake error caused by the commit 9635494bf.