Add support Camel Case for key to avoid crash

[vsay01]

Hopefully it support the camel case for the key

[pforhan]

You'd have to adjust tests, too. For what it's worth, there's already #35 that clarifies the error messages.

[vsay01]

@pforhan It seems test case illegalTokenCharactersFailFast will fail if we use Camel Case for the token. Also in #35 there is a test case putFailUppercaseNotAllowedMiddle as well.
Does the library want to support only the lowercase and _ for token?

For my case, i need to have Camel Case that's why I thought it would be useful for others as well. Would love to hear the direction from you, I can either close this PR or fix the unit test. Thanks

[vsay01]

For now I fix the unit tests in my local branch, and all the test cases are passed.
If the library want to support the Upper case then I will make the following commit so that the build pass.

   //commented out this test case to support if want to support Upper Case
   /*@Test public void illegalTokenCharactersFailFast() {
      try {
        from("blah {NoUppercaseAllowed}");
        fail("Expected IllegalArgumentException");
      } catch (IllegalArgumentException e) {
      }
    }*/

    @Test
    public void tokenCanHaveUpperCase() {
        assertThat(from("blah {UppercaseAllowed}").put("UppercaseAllowed", "Uppercase Allowed").format().toString()).isEqualTo(
                "blah Uppercase Allowed");
    }

[pforhan]

If you look at the issue history (like #9) , there's not been a lot of desire for it, that's why I beefed up the error messages and tests to be more explicit about the expected key format.

[vsay01]

@pforhan Thanks for the information. I will close this pull request as the library won't support the Upper case as the choice of the library as mentioned in #9.
For all who need support for upper case, you can find Fixes #17 provided the fix or visit my forked repo. .
i planned to support as well:

#{token}

Thanks for the library.