submodules: update rls from 90f7ab0 to 49efc06

Changes:
````
Account for changed format range in a test
Adapt format integration test to use new range
Add unit tests for Rustfmt::calc_text_edits
Prefer saturating_sub
Return only partial text edits on formatting request
Redo errors in format.rs
Rephrase unstable features helper function
Work around Rustfmt bug
Adjust range-formatting test
Update Rustfmt to 1.2
Allow unstable features under "dev" channel
Updated clippy_lints in to rev c81e43b to fix build breaking
Fix lint pass API changes
Remove a redundant import
Bump Clippy
Add more helpful compiler messages when the features are improperly specified
Silence some flaky tests.
Update Cargo.
Rename read_analysis to decode_buf
Update Clippy
Fix pointer to pointer silliness
Add serde implementation to complement rustc-serialize
````