@saleem: unit tests for the text converter solution

# Important Point 1 #

I renamed the package of UnicodeFileToHtmlTextConverter from 
```
tddmicroexercises.textconvertor 
```
to 
```
tddmicroexercises.textconverter
```
If you didn't spot the difference; I don't blame you! The new package name spells "converter" with *t-E-r*, instead of *t-O-r*. This is to make it consistent with the classname. 

# Important Point 2 #

I added unit tests for the UnicodeFileToHtmlTextConverter *without refactoring or changing it in any way* -- other than the package-name change described above. This is because I wanted to remain true to the spirit of the exercise: if this was a _real_ project with legacy ( = untested) code, I wouldn't want to touch it before I had sufficient tests around it. This current commit has tests but no changes to the the SUT. Potentially, a _subsequent_ commit could do proper refactoring of the UnicodeFileToHtmlTextConverter class.