Compatibility with Android < 2.3 and Java < 6

String's isEmpty() is not available in Android < 2.3 and Java < 6. To
fix this two uses of isEmpty() were replaced with length() == 0. This
is more ugly but allows using this library on two outdated platforms.
Merge pull request #8 from philippwiesemann/fix-compatibility

Compatibility with Android < 2.3 and Java < 6
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	src/main/java/com/osbcp/cssparser/CSSParser.java
Merging remote main into branch.
Removing static attribute from identifier.
Removing CharSequence parse method as it's redundant, the String version will work for CharSequence types too.