rename auth api and fix some bugs

[javeme]

• add 'auth' category before all auth APIs
• fix unable to removeEdge() when enable auth
• fix delete admin user(expect not allowed)
• check auth element not exist before creating
• throw 400 instead of 404 when delete non-exist element

Change-Id: Id8c4f39195f9f6cea95fdbe591592b0f1baf0627

[codecov]

Codecov Report

Merging #1033 into master will decrease coverage by 0.09%.
The diff coverage is 44.00%.

@@             Coverage Diff              @@
##             master    #1033      +/-   ##
============================================
- Coverage     69.20%   69.11%   -0.10%     
- Complexity     5403     5423      +20     
============================================
  Files           328      329       +1     
  Lines         26334    26370      +36     
  Branches       3750     3757       +7     
============================================
+ Hits          18225    18226       +1     
- Misses         6331     6362      +31     
- Partials       1778     1782       +4     

Impacted Files	Coverage Δ	Complexity Δ
...n/java/com/baidu/hugegraph/api/auth/AccessAPI.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...n/java/com/baidu/hugegraph/api/auth/BelongAPI.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...in/java/com/baidu/hugegraph/api/auth/GroupAPI.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...n/java/com/baidu/hugegraph/api/auth/TargetAPI.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...ain/java/com/baidu/hugegraph/api/auth/UserAPI.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...a/com/baidu/hugegraph/auth/HugeGraphAuthProxy.java	4.27% <0.00%> (-0.02%)	0.00 <0.00> (ø)
...in/java/com/baidu/hugegraph/StandardHugeGraph.java	80.00% <0.00%> (ø)	106.00 <9.00> (ø)
...main/java/com/baidu/hugegraph/auth/HugeBelong.java	84.84% <ø> (ø)	16.00 <0.00> (ø)
.../main/java/com/baidu/hugegraph/auth/HugeGroup.java	84.28% <ø> (ø)	16.00 <0.00> (ø)
...in/java/com/baidu/hugegraph/auth/HugeResource.java	77.27% <ø> (ø)	41.00 <0.00> (ø)
... and 19 more

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