Fixed a parsing bug in MethodInvocation

When parsing 'System.out.println("Yeay!")',
We should get MethodInvocation(name='println',
target=Name('System.out'), ...), not
MethodInvocation(name='System.out.println', target=None).

Unfortunately, It parses the expression into the latter one.
I fixed it.
fix 'line comment at last line' parsing error

If input ends with a line comment without new line,
parsing fails.
fix abstract method parse tree

interfaces' methods should be parsed as
MethodDeclaration.
Merge branch 'fix_abstract_method' of github.com:jooyunghan/plyj into jooyunghan-fix_abstract_method
Merge branch 'parser_fix' of github.com:Algy/plyj into algy-parser_fix
fix failing test for method invocation
fix a regex for a line comment

The previous regular expression for a line comment requires that //
should be immediately followed by a character other than the backslash
or newline character. So it did not allow 1) a line comment whose whole
line just consists of // or 2) a line comment where // is immediately
followed by the backslash character.
Merge pull request #17 from dkim/fix_line_comment

Fix a regular expression for a line comment
Merge remote-tracking branch 'musikk/master'

Conflicts:
	plyj/parser.py