Issue 1566 enforce has one

[amitsuryavanshi]

Fixes #1566

This pull introduces/changes:

• confing flag enforce_has_one. When flag is set, as the relationship is created on reverse object with another object, raises the error.
• by default flag is not set

[codecov-io]

Codecov Report

Merging #1567 into master will increase coverage by <.01%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1567      +/-   ##
==========================================
+ Coverage   93.22%   93.23%   +<.01%     
==========================================
  Files         105      105              
  Lines        4771     4774       +3     
==========================================
+ Hits         4448     4451       +3     
  Misses        323      323

Impacted Files	Coverage Δ
lib/neo4j/active_node/rels.rb	71.42% <ø> (-14.29%)	:arrow_down:
lib/neo4j/active_node/has_n.rb	99.24% <100%> (+0.02%)	:arrow_up:
lib/neo4j/active_rel/persistence.rb	95.71% <100%> (+0.06%)	:arrow_up:
lib/neo4j/active_node/query/query_proxy.rb	95.09% <100%> (ø)	:arrow_up:

---

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Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 4ea065a...033e1c2. Read the comment docs.

[codecov-io]

Codecov Report

Merging #1567 into master will increase coverage by <.01%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1567      +/-   ##
==========================================
+ Coverage   93.22%   93.23%   +<.01%     
==========================================
  Files         105      105              
  Lines        4771     4774       +3     
==========================================
+ Hits         4448     4451       +3     
  Misses        323      323

Impacted Files	Coverage Δ
lib/neo4j/active_node/rels.rb	71.42% <ø> (-14.29%)	:arrow_down:
lib/neo4j/active_node/has_n.rb	99.24% <100%> (+0.02%)	:arrow_up:
lib/neo4j/active_rel/persistence.rb	95.71% <100%> (+0.06%)	:arrow_up:
lib/neo4j/active_node/query/query_proxy.rb	95.09% <100%> (ø)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 4ea065a...f038ec6. Read the comment docs.