Added "dir" argument to javaimport-get-all-classes-defined-in-html-files provider according to class provider contract.

As seen is the definition of javaimport-get-all-classes-defined-in-dir, each provider is called given
two arguments: dir &optional token
Thus the HTML class provider must also accept a "dir" argument (which is ignored) to be called without error (wrong
number of arguments).
Add the function to detect the root directory of the project in which the current source code file depends.

It achieves its goal by searching for certain file patterns corresponding to build files (like Ant build.xml
or gradle build.gradle) based on current file extension (currently both .java and .groovy extension are treated
by looking for the same patterns). An unknown file extension will be treated by looking for a default set of
build file patterns. (Actually, all extensions , both .java, .groovy and unknown extensions refer to the same
set of default extensions ([Bb]uild[.]xml" ".+[.]pom" ".+[.]gradle" "src"))

The set of extensions and patterns associated to them may be refined in future.