correct spelling mistakes

A few spelling fixes for the git-annex devblog.

doc/devblog/day_452__GIT_SSH.mdwn

@@ -7,7 +7,7 @@ suites should not do. So, I took a detour..
 
 Support for `GIT_SSH` and `GIT_SSH_COMMAND` has been requested before for
 various reasons. So I implemented that, which took 4 hours. (With one
-little possible compatability caveat, since git-annex needs to pass the -n
+little possible compatibility caveat, since git-annex needs to pass the -n
 parameter to ssh sometimes, and git's interface doesn't allow for such a
 parameter.)
 

doc/devblog/day_463-465__back_buggy_external_special_remotes.mdwn

@@ -10,7 +10,7 @@ run to vary what remotes are used depending on eg, what network it's on.
 
 Also, I took a look at the external special remote protocol, and noticed
 two problems with it. First, keys with spaces in their names can't be used
-with it. This only affects the WORM backend, and it seems noone has ever
+with it. This only affects the WORM backend, and it seems no one has ever
 run into the problem. Rather than complicate the implementation of external
 special remotes, I decided to deprecate having spaces in key names. Which
 is just asking for trouble anyway. So now there's a nice error message, and

doc/devblog/day_472__removing_empty_directories.mdwn

@@ -8,7 +8,7 @@ So, I decided to add a remote method to delete a directory, and make
 git-annex keep track of when a directory in an export is empty, and delete
 it. While it does complicate the design some to need to do this, that seems
 better than complicating the implementation of remotes like webdav. And
-some remotes may not have a `rmdir(2)` equivilant or a way to check if a
+some remotes may not have a `rmdir(2)` equivalent or a way to check if a
 directory is empty.
 
 Spent most of today implementing that, including some rather hairy