language changes: #![crate_id] -> #![crate_name].
Merge pull request #89 from lifthrasiir/crate-name

Language changes: #![crate_id] -> #![crate_name].
Fixed cargo setup
Merge pull request #90 from mmerfort/master

Fixed cargo setup
Adjust for cargo and new directory layout
Adjust name
Adjust name
Fix --test build
Merge pull request #91 from ebfe/fix-test

Fix --test build
try to use cargo
do not install rust-nightly via apt-get
language changes: std::str::raw::from_c_str is deprecated; fixed some testing issues.
revamped `Cursor::get_{text,blob}` functions. closes #92.

they used to return a direct `String` or `Vec<u8>`, which may fail
when it should return `NULL`. other functions do not have this issue
since the automatic conversion is fully defined over INTEGER and
FLOAT internal types.

this commit changes them to return an optional `&str` or `&[u8]`.
this correctly handles `NULL`, and moreover, reduces the redundant
allocations when the buffer doesn't need to be kept. this also
makes `Cursor::get_bytes` fully redundant, so it has been removed.